Number 7 Volume 20
July
2014
Number 7
Volume 20
‫تموز‬
‫العدد ‪7‬‬
‫المجلد ‪02‬‬
‫‪0224‬‬
College of Engineering
University of Baghdad
List of Contents
English Section:
Assessing Durability of Roller Compacted Concrete
Page
1 - 14
Prof. Saad Issa Sarsam
Lect. Abeer Abdulqader Salih
Sura Dheyaa Tawfee
A Proposed Management System for Construction Practices during Sustainable
Buildings Life Cycle
15 - 35
Dr.Angham E. Al-Saffar
Zeena Hameed Salman
Design and Implementation of ICT-Based Recycle-Rewarding System for Green
Environment
36 – 47
Dr. Mohammed Issam Younis
Experimental Studies and Finite Element Modeling of Piles and Pile Groups in
Dry Sand under Harmonic Excitation
48 -61
Saad Faik Abbas Al-Wakel
Mahmoud Rasheed Mahmoud
Ahmed Sameer Abdulrasool
An Experimental Analysis of Embankment on Stone Columns
62 - 84
Dr.Mohammed Y.Fattah
Dr. Bushra S.Zabar
Hanan A. Hassan
A Multi-variables Multi -sites Model for Forecasting Hydrological Data Series
85 - 102
Rafa H. Al-Suhili
Nawbahar F. Mustafa
Removal of Water Turbidity by using Aluminum Filings as a Filter
Media
103 – 114
Dr. Abeer Ibrahim Alwared
Suhair Luay Zeki
The Effect of Dynamic Loading on Stresses Induced in Charnley Hip Prosthesis
115 - 129
Ahmed Abdul Hussain
Mahmood Wael Saeed
Structural Behavior of Reinforced Concrete Hollow Beams under Partial
Uniformly Distributed Load
130 - 145
Ahmad Jabbar Hussain Alshimmeri
Hadi Nasir Ghadhban Al-Maliki
An Analysis of Stress Distribution in a Spline Shaft Subjected To Cycilc
Impulsive Load
Ass. Prof. Dr. Fathi A. AL- Shammaa
Hawaa F. Kadhim
146 - 157
Study of Dynamic Sorption in Adsorption Refrigeration Cycle
Adil A. Al-Hemiri
Mohammed A. Atiya
Farkad A. Lattieff
The Effect of Hydraulic Accumulator on the Performance of
Hydraulic System
Dr.Jafar Mehdi Hassan
Moayed Waleed Moayed
158 – 173
174 - 190
Number 7
Volume
20
July
-
2014
Journal of Engineering
Assessing Durability of Roller Compacted Concrete
Prof. Saad Issa Sarsam
Lect. Dr. Abeer Abdulqader Salih
Department of Civil Engineering
Department of Civil Engineering
College of Engineering
Sura Dheyaa Tawfee
Department of Civil Engineering
College of Engineering
College of Engineering
Baghdad University
Baghdad University
Baghdad University
Email: [email protected]
[email protected]
ABSTRACT
R
oller Compacted Concrete (RCC) is a technology characterized mainly by the use of rollers for
compaction; this technology achieves significant time and cost savings in the construction of dams and
roads. The primary scope of this research is to study the durability and performance of roller compacted
concrete that was constructed in the laboratory using roller compactor manufactured in local market. A total
of (60) slab specimen of (38×38×10) cm was constructed using the roller device, cured for 28 days, then 180
sawed cubes and 180 beams are obtained from RCC slab. Then, the specimens are subjected to 60 cycles of
freezing and thawing, sulfate attack test and wetting and drying. The degree of effect of the type of coarse
aggregate (crushed and rounded), cement type (OPC and SRPC) and cement content on the durability of
RCC were investigated. The results indicated that RCC that contain SRPC has beneficial effects on
properties of RCC as compared to RCC that contain OPC after durability testing. Based on the testing
results, it was concluded that the resistance of RCC specimens to freezing and thawing, wetting and drying
and sulfate attack test increase as cement content increase. The results also indicate that using RCC that
contain crushed aggregate has a positive effect on the overall properties of RCC, as compared with RCC that
contain rounded aggregate after durability testing.
Keywords: roller compacted concrete, durability, freezing and thawing, sulfate attack test, wetting and
drying.
‫تقييم ديمومة الخرسانة المرصوصة بالحدل‬
‫سرى ضياء توفيق‬
‫قسم الهندسة المدنية‬
‫جامعة بغداد‬/‫كمية الهندسة‬
‫عبير عبد القادر صالح‬.‫د‬.‫م‬
‫قسم الهندسة المدنية‬
‫جامعة بغداد‬/‫كمية الهندسة‬
‫ سعد عيسى سرسم‬.‫ا‬
‫قسم الهندسة المدنية‬
‫جامعة بغداد‬/‫كمية الهندسة‬
‫الخالصة‬
ٍ‫ُز‬،‫حعخبش الخشساًت الوشطْطت بالحذل هي الخقٌ٘اث الخٖ حعخوذ بالذسجت األكبش خاط٘ت إسخعوال الحادالث لشص الخشساًت‬
‫ اى الِذف الشئ٘سٖ هي ُزا البحث ُْ دساست دٗوْهت ّاداء‬.‫الخقٌ٘ت حْفش ّححفظ الْقج الوِن ّالكلفت فٖ إًشاء السذّد ّ الطشق‬
ٖ‫ٗخضوي الجضء العول‬0 .‫الخشساًت الوشطْطت بالحذل الخٖ حن حظٌ٘عِا هخخبشٗا بأسخخذام جِاص حذل طٌع فٖ االسْاق الوحل٘ت‬
ٍ‫ ثن حن حقط٘ع ُز‬،‫ ْٗم‬28 ‫بعذ رلك اًضجج لوذة‬،‫) سن‬٠١×٨٣×٨٣( ‫) بالطت خشساً٘ت هشطْطت بالحادلت بأبعاد‬60( ‫ححض٘ش‬
ّ ‫ فحض حأث٘ش الكبشٗخاث‬, ‫ دّسٍ هي االًجواد ّالزّباى‬60ّ30 ٔ‫ حن حعشٗض الٌوارج ال‬.‫)عخبت‬180( ّ ‫) هكعب‬180( ٔ‫البالطاث ال‬
‫ حن دساست ًْع السوٌج ( السوٌج البْسحالًذٕ االعخ٘ادٕ ّ السوٌج الوقاّم للكبشٗخاث) ّحأث٘ش هحخْٓ السوٌج‬.‫الخشط٘ب ّالخجف٘ف‬
‫ هي خالل الٌخائج الخٖ حن الحظْل علِ٘ا ّجذ اى هقاّهت الٌوارج الحاّٗتعلٔ السوٌج‬.‫علٔ دٗوْهت الخشساًت الوشطْطت بالحادلت‬
ٕ‫الوقاّم للكبشٗخاث لَ حأث٘ش اٗجابٖ علٔ خْاص الخشساًت الوشطْطت بالحذل هقاسًت هع الٌوارج الحاّٗتعلٔ السوٌج البْسحالًذ‬
‫ اعخوادا علٔ ًخائج الفحْطاث حن االسخٌخاج اٗضا بأى هقاّهت ًوارج‬.‫االعخ٘ادٕ بعذ حعشٗض الٌوارج الٔ فحْطاث الذٗوْهت‬
‫ الخشط٘ب ّ الخجف٘ف ّ فحض هقاّهت حأث٘ش الكبشٗخاث حضداد بضٗادة‬, ‫الخشساًت الوشطْطت بالحذل لذّساث االًجواد ّالزّباى‬
. ‫هحخْٓ السوٌج‬
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1. INTRODUCTION
The American Concrete Institute (ACI) defines RCC as “concrete compacted by roller compaction;
in its unhardened state, will support a roller while being compacted.” Properties of hardened RCC can be
similar to those of conventionally placed concrete. The term “roller compaction” is also defined by ACI as “a
process for compacting concrete using a roller, often a vibrating roller. USACE , 2000.
Kreuer ,2006, defined Roller Compacted Concrete as a dry concrete consisting of more aggregate
and less cement paste than conventional concrete. Because cement is the most expensive constituent of
concrete, RCC is less expensive in terms of cost of materials.
Due to its dry nature, RCC has a zero slump and it is placed without forms or finishing. RCC
pavements do not require joints, dowels, or reinforcing steel. Relatively large quantities of RCC pavement
can be placed rapidly with minimal labor and equipment, enabling speedy completion of tightly scheduled
pavements.
RCC is used for the construction of dams and pavements, Chun et al , 2008. RCC first was used to
build dams. Besides the reduced construction cost resulting mainly from labor and equipment savings, its
principal advantage for mass construction is the low cement content of the mixture which greatly reduces
problems due to the heat of hydration of cement, PCA , 2004.
RCC pavement is much stronger and durable than asphalt pavement. RCC will not rut from high axle
loads, or shove or tear from turning or braking of operating equipment. It will not soften from heat generated
by hot summer sun or material stored on RCC floors. RCC resists degradation from materials such as diesel
fuel, Naik et al , 2001.
The primary differences in proportions of RCC pavement mixtures and conventional concrete
pavement mixtures are, ACI 325-10R-, 1995.
• RCC is generally not air-entrained;
• RCC has lower water content;
• RCC has lower cement paste content;
• RCC generally requires a larger amount of fine aggregate in order to produce a combined aggregate that is
well-graded and stable under the action of a vibratory roller. RCC pavements, like all other types of concrete
elements, can be subjected to many types of deterioration such as abrasion/erosion, freezing and thawing,
wetting and drying, and other factors such as alkali-silica reaction, and sulfate attack. RCC is now
increasingly used for the construction of pavements exposed to very severe loading and environmental
conditions, PCA , 2004.
RCC is not just more economical than the currently used pavement alternatives, but has also shown
high durability and early gain of mechanical strength in both the field and the laboratory, Kreuer 2006.
RCC has been used in Iraq in mid-eighties below the foundations of the medical drug factory near
Mosul and also in the AL-Adaim Dam, Ahmed , 2001. Another reported use was in the construction of extra
lane for Mosul- Duhok highway in 1988, Sarsam , 2002.
1.1 Objective of the Study
The objective of this research is to assess durability and performance of a test slab that was constructed
by using roller compactor machine. The main aims of this study are as follows:
1- Studying degree of effect of freezing and thawing cycles, wetting and drying cycles and sulfate
attack on the modulus of rupture of RCC slabs.
2- Investigating degree of effect of cement type and cement content on the performance of RCC slabs
during durability testing.
2 . EXPERIMENTAL WORK
2.1 Material Characteristics
2.1.1 Cement
Both ordinary Portland cement (OPC) and sulfate resisting Portland cement (SRPC) manufactured in
Iraq with a commercial name of (Tasluga, Al-jesser) is used for RCC mixes throughout the present work.
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2.1.2 Aggregate
Crushed gravel with a nominal size of (19 mm) brought from Nibaai region is used in this work. The
aggregate is washed and cleaned by water. Later, it is air dried and separated into different sizes. Fine
aggregate (passing sieve No.4 BS.) brought from Al-Ukhaider region are used in this work. The sand is
washed and cleaned by water. Later, it is air dried and separated into different sizes.
2.1.2.1 Gradation of Coarse and Fine Aggregate
Dense gradation usually used for asphalt concrete pavement in Iraq has been adopted for this
investigation. The coarse and fine aggregates are sieved to different sizes; the desired weight of each size of
aggregate is taken and combined to satisfy the requirements of gradation. The design over all gradation of
aggregate is selected by using of State Commission of Roads and Bridges SCRB , 2004. The grain size
distribution is illustrated in Table 1.
2.1.3 Water
The water used in RCC mixes was drinking water of Baghdad area. This water was also used for
curing.
2.2 Mix Design and Proportions of RCC Samples
The concrete mix is designed according to previous experience Abdullah , 2011. .Three different
percentages of cement content has been selected (10 %, 12 %, and16 %) by weight of air dried aggregate and
three different percentages of moisture content are used. The details of dry density at different moisture and
cement contents are summarized in Table 2. Four types of mixes are adopted with three percentages of
cement and
three percentages of moisture content for each mix; the types of mixes are as following:
1- Crushed aggregate + Natural sand + Ordinary Portland cement
2- Crushed Aggregate + Natural Sand + Sulfate resisting Portland cement.
2.3 Casting of RCC Slab Samples
2.3.1 The Molds
The steel molds manufactured in local workshop are used in this investigation. It consists of four
sides made from angle section steel of (100×100×10 mm) with steel plate of (650×600×10 mm), the sides
and plate are connected together by bolts and two handles are welded with the plate to easy lift the mold and
put on the vibrating table, the total weight of one mold is 51kg. A slab specimen having size of
(380×380×100mm) is obtained from this mold. Molds details of slab specimens are shown in Fig.1.
2.3.2 The Roller Device
The device consists of a steel roller of 160mm diameter, 330 mm in length and 15 kg in weight is fixed by
two bolts with device ,steel box of (600 ×460×180) mm is used to add various standard weights up to 138kg
for applying loads on the roller to simulate the field conditions ,this box is connected by welding above the
device, and two small wheels connected in the back direction for easy transporting the device during the
work and two hands support is welded in the back of the device to easing push the device during the rolling
as shown in Fig.2 The total weight of this apparatus is 36 Kg.
2.3.3 Mixing
Before mixing the materials molds are prepared by cleaning, and their internal surfaces are covered
by using nylon sheets to prevent loss of the water or material from sides during the rolling and to prevent
adhesion with concrete after
hardening, after that for two minutes the cement and aggregate are dried mixed by hand mixing then a hole is
formed at the mixture in the middle .Then required amount of water is poured and mixed for five to six
minutes to achieve homogeneous mixture.
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2.3.4 Compaction
2.3.4.1 Compaction by vibrating table
The mixture is placed in the mold and subjected to initial compaction on a vibrating table for 3
layers of 30 seconds time interval.
2.3.4.2 Compaction by using a roller device:
The mold is fixed in front of the roller compactor device and subjected to three stages of rolling
based on the work done by Sarsam ,2002. Abdullah ,2011. and Abdulrahim ,2011. for each stage10
passes is applied .This number of passes is suitable to achieve the good rolling with low labor , and the
rolling action is taken in x-x direction , then the same sequence have been repeated in the y- y direction as
shown in the Fig.3 . This is to insure the compaction of the slab sides. The first stage represent the initial
compaction in the field, a total load of 1.1 kg/cm width (by using roller compactor weight only) is applied
with 10 passes of the roller in each direction. The concrete is settled in a level position and completely fill
the slab mold and gives a level surface, the compaction by using a roller device is shown in Fig.4.
The second stage may simulate the intermediate field compaction; a total load of 3.2 kg/cm width
(by using 6 standard loads each load of 11.5 kg plus roller compactor weight) is applied with 10 passes of the
roller in each direction. The final stage represents the finishing compaction in the field a total load of
5.3kg/cm width (by using 12 standard loads each load of 11.5 kg plus roller compactor weight) is applied
with 10 passes of the roller in each direction.
2.3.5 Curing
After molding and finishing the compaction, the surface of casted samples is leveled by hand
trawling and covered with polyethylene sheet to prevent evaporation of moisture from the fresh concrete, and
left in lab
at room temperature of 30±5˚c to next day for setting then, the samples are taken out of the molds. Then, the
specimens are immersed in the curing tank for (28) days at 30±5˚c. Part of RCC slab specimens after 28 day
curing is shown in Fig. 5.
2.3.6 Cutting of RCC slab specimens
By using the procedure of ASTM C42/C42M-(2003) sawed cubes and beams are obtained from RCC
slab specimens, a total of 180 cubes of (100×100×100 mm) are obtained from slab specimens, and 180
beams of (380×80×100mm) are also obtained from slabs specimens. Samples obtained from RCC slab is
shown in Fig. 6.
2.4 Durability Investigations
2.4.1 Freezing and thawing test
The freezing and thawing test is carried out according to ASTM C-666-(2002) procedure B, (rapid
freezing in air and thawing in water). Freezing and thawing tests are started by placing the specimens (4
cubes and 4 beams from each mixes) in the thawing water at the beginning of the thawing phase of the cycle
at temperature 30 ± 3 ₀ C for 2 ½ hr to ensure that the specimens are completely thawed then, the specimens
are taken out of water and are placed in deep freezer at temperature ( -11± 1₀ C) for 4 ± ½ hr as the
beginning of the freezing phase of the cycle. This procedure is repeated for 60 cycles of freezing and
thawing.
2.4.2 Sulfate attack test
Resistance of RCC specimens to disintegrate by saturated solution of sodium sulfate is determined
according to ASTM C –88 (1999).
2.4.3 Wetting and drying cycles
The RCC specimens are subjected to cycles of wetting and drying in the light of many research
works Mahmoud ,1977. AL-Delaimee , 1989. Ahmed, 2001, and Riyadh , 2005. The cycles are started
by placing the specimens (4 cubes and 4 beams from each mixture) in the oven at temperature 70 ₀ C for 24
hr. Then, it is removed from oven and it is immersed in water for 24 hr at
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28 ₀ C .The alternate immersion and drying of specimens are repeated for 60 cycles.
2.5 Modulus of Rupture Test
The modulus of rupture is determined by using sawed beams of sizes (380×100×80) mm according
to ASTM C293-(2003).
3. ANALYSIS AND DISCUSSION OF TEST RESULTS
3.1 Effect of Type of Cement and Cement Content on Modulus of Rupture of RCC
during Freezing and Thawing Cyclic
Modulus of rupture of RCC that made of sulfate resisting Portland cement shows higher values than
that RCC made of ordinary Portland cement before and after subjected to freezing and thawing cycles as
shown in Table 3.
When testing beam specimen with 16% sulfate resisting Portland cement at 60 cycles of freezing and
thawing the modulus of rupture is higher than that of specimens that have ordinary Portland cement by
14.285% as shown in Fig.7.This happens because the strength is developed rapidly for finer cement since the
rate of hydration depends on the fineness of cement particles, where the surface area of cement represents the
material available for hydration. This affects the resistance of cement paste and amount of water that able to
freeze in it.
It can be seen that the modulus of rupture of sawed beams which obtained from RCC slab samples
increases with increasing cement content. Specimens tested after 60 cycles of freezing and thawing shows
increasing in modulus of rupture as cement content increase, the range of this increase is (22.43 -11.36%) for
(OPC) .This may be attributed to the cement availability for hydration filling the voids, this will give better
permeability and create stronger bonds within the concrete matrix and thus provide more resistance to frost
damage in concrete were based up on the expansion of ice upon freezing and the subsequent stress , This
agrees with stutzman , 1999. The durability can be improved by increasing cement content, Balaguru and
Ramakrishnan , 1986.
Table 4 shows percentage of decrease in modulus of rupture of RCC that subjected to alternate
freezing and thawing cycles, while Fig. 8 shows the relationship between percentages of decrease in modulus
of rupture with cement content for RCC made of OPC and SRPC.
The result also shows that the modulus of rupture of RCC decreases as the cycles increase. It can be
seen from Table 4 that the modulus of rupture at 60 cycles for beam specimens with 10% ordinary Portland
cement shows maximum reduction of 12.213% , while beam specimens with 10% sulfate resisting Portland
cement shows maximum reduction at 60 cycles of 6.619% . The reason of decreasing in strength is internal
damage result from freezing and thawing cycles causes microscopic cracks in the cement paste leading to
change in mechanical parameters of the concrete. This agrees with Petersen , 2007.
3.2 Effect of Type of Cement and Cement Content on Modulus of Rupture of RCC
during Wetting and Drying Cyclic It is clear from the test results that the modulus of rupture of RCC
made of SRPC cement is higher than that OPC before and after subjecting specimens to cycles of wetting
and drying as shown in Table 5 .
When 16% sulfate resisting Portland cement is used the results show modulus of rupture higher than that
ordinary Portland cement by 14.602% at 60 cycles of wetting and drying. This may be attributed to that
the rate of hydration will be reduced at each drying period for ordinary and sulfate resisting Portland
cement but the strength of sulfate resisting Portland cement still developed faster than that ordinary Portland
cement because SRPC is finer than OPC and the rate of hydration depends on the fineness of cement
particles. Fig. 9 shows the relationship between modulus of rupture and number of cycles for RCC made of
ordinary and sulfate resisting Portland cement.
From the results in Table 5, it can clearly be seen that the modulus of rupture increases with
increasing cement content before and after cycles of wetting and drying. The percentage of increasing in
modulus of rupture is 21.815% when ordinary Portland cement content changes from 10% to 12% and
9.885% increasing in modulus of rupture when cement content changes from 12% to 16%. This trend may be
attributed to higher cement content created stronger bonds within the concrete matrix and this provide more
resistance to microcracks that result from drying process.
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Table 6 shows percentage of decrease in modulus of rupture of RCC that subjected to wetting and
drying cycles, Fig.10 shows the relationship between percentage of decrease in modulus of rupture with
cement content for RCC made of OPC and SRPC.
It can be seen that the modulus of rupture decrease as the cycles increase. The percentage of decrease
in modulus of rupture at 30 and 60 cycles for RCC made of 12% ordinary Portland cement is 4.545% and
9.350% respectively than modulus of rupture at zero cycle, and the percentage of decrease in modulus of
rupture at 30 and 60 cycles for RCC made of 12% sulphate resisting Portland cement is 3.899% and 8.050%
respectively than modulus of rupture at no cycle. The reduction in strength is due to induces microcracks in
RCC material and the rate of hydration will be reduced at each drying period.
3.3 Effect of Type of Cement and Cement Content on Modulus of Rupture of RCC
during Sulfate Attack Cyclic
It is clear from the test results that modulus of rupture of RCC made of SRPC is higher than that
RCC made of OPC before and after subjecting 60 cycles of wetting in sodium sulfate solution and drying as
shown in Table 7 . RCC made of 16% SRPC shows modulus of rupture higher than RCC made of OPC by
17.227% at 60 cycles .This is because sulfate resisting Portland cement have lower content of C 3A that
react with sulfate ion and form ettringite. Fig. 11 shows the relationship between modulus of rupture and
number of cycles for RCC made of ordinary and sulfate resisting Portland cement.
It is clear from the test result that the modulus of rupture before and after 30 and 60 cycles of wetting
in sulfate solution and drying increase as cement content increase , specimens tested after 30 cycles and that
content 12% and 16% OPC shows increasing in modulus of rupture as compared to reference RCC mix at
10% by 19.7% and 30.4% respectively ,and specimens tested after 60 cycles and that content 12% and 16%
SRPC shows increasing in modulus of rupture as compared to reference RCC mix at 10% by 21.26% and
33.8% respectively. This happens because at high cement content the concrete is higher density than that low
cement content and this leads to make the concrete less permeability and the resistance of concrete to sulfate
attack is depended on its permeability, Neville , 1995.
It can be seen from Table 8 that after 30 and 60 cycles of immersion in sodium sulfate solution and
drying RCC made of 12% ordinary Portland cement shows percentage of decrease in modulus of rupture by
6.103% and 12.597 % respectively than that modulus of rupture at no cycles, and specimens which have
12% sulfate resisting Portland cement shows after 30 and 60 cycles of immersion and drying percentage of
decrease in modulus of rupture by 4.150% and 7.924% respectively than that modulus of rupture at zero
cycles. The reduction in modulus of rupture can be attributed to the same reasons of decrease in compressive
strength. Fig. 12 shows the relationship between percentage of decrease in modulus of rupture with cement
content for RCC made of OPC and SRPC.
4. CONCLUSIONS
1- The modulus of rupture RCC mixes decrease with the increase in freezing and thawing cycles,
alternating wetting and drying cycles, and with increasing the number of immersion cycles in
sodium sulfate solution and then drying.
2- The resistance of RCC to freezing and thawing cycles, wetting and drying cycles and sulfate
attack test increases with increasing cement content.
3- RCC made of sulfate resisting Portland cement gave better durability than RCC made of
ordinary Portland cement when subjecting the specimens to 60 cycles of freezing and
thawing. Modulus of rupture was higher for samples containing sulfate-resisting cement, as
compared with ordinary Portland cement by 14.285% at 16% cement content.
4- Resistance of RCC mixes to sulfate attack test cycles was improved when using Sulfate
resisting Portland cement as compared with the ordinary Portland cement, the modulus of
rupture of samples exposed for 60 cycles and containing Sulfate resisting cement is higher
than the resistance of samples containing ordinary Portland cement by 17.227% at 16%
cement content.
5- Resistance of RCC containing sulfate-resisting cement is better than specimens containing
ordinary Portland cement when exposed to cycles of wetting and drying. The increase in the
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modulus of rupture of the samples containing Sulfate resisting cement when exposed to 60
cycles of wetting and drying is 14.602% at 16% cement content.
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Department of Civil Engineering and Mechanics, College of Engineering and Applied Science ,The
University Of Wisconsin, Report No. CBU-2008-03, March.
Kreuer, B., 2006, Bond Shear Strength Of A Rigid Pavement System With A Roller Compacted Concrete
Base, department of Civil Engineering, Cleveland State University, PCA , Serial No.2990, May.
7
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Journal of Engineering
Mahmoud, T.K., 1977, The Effect Of Sulfates And Cyclic Wetting And Drying On The Physical Properties Of
Concrete, M.SC., Thesis, Department Of Civil Engineering, University Of Baghdad, June.
Naik, T.R., Chun, Y-M., Kraus, R.N., Singh, S.S., Pennock, L-L.C., and Ramme, B.W., 2001, Strength and
Durability of Roller-Compacted HVFA Concrete Pavements, Department of Civil Engineering and
Mechanics, College of Engineering and Applied Science, The University of Wisconsin – Milwaukee,
Accepted for Publication in the ASCE’s Practice Periodical on Structural Design and Construction, Report
No. CBU-2001-08, REP-434, March .
Neville, A. M., 1995, Properties of Concrete”, 4th Edition, Pittman Publishing Limited, London.
PCA 2004, Frost Durability of Roller-Compacted Concrete Pavements, RD135, Portland Cement
Association, Skokie, Illinois, USA, 2004, 148 pages
Petersen, L, Lohaus, L., and polak, M.A. , 2007, Influence Of Freezing And Thawing Damage On Behavior
Of Reinforced Concrete Elements, ACI Materials journal, Vol. (104), No. (4), July-august, 2007,pp(369378).
Riyadh, M .J., 2005, Some Factors Affecting Properties And Behavior Of Roller Compacted Concrete In
Embankments, Ph.D., Thesis, Department of Civil Engineering, University of Baghdad, January.
Sarsam S.I., 2002 Evaluation of Roller Compacted Concrete pavement Properties Engineering and
Development Scientific Journal of Al-Mustansiria University, Vol. (6), No. (1), March, 2002, pp. (59-74).
SCRB, 2004 ,State commission of roads and bridges Ministry of Housing and construction, 2004, Iraq.
Stutzman, P. E. , 1999, Deterioration of Iowa Highway Concrete Pavements: A Petrographic Study,
Building And Fire Research Laboratory ,National Institute of Standards And Technology,
United States Department Of Commerce Technology Administration, December.
USACE (U.S. Army Corps of Engineers), 2000," Roller-Compacted Concrete", Engineer Manual,
Department of the Army, Washington, DC 20314-1000, January.
Sarsam S., AL-Rawi A. and Tawfeeq S. , 2014, Durability Assessment of Roller Compacted Concrete Using
NDT,American Journal of Civil and Structural Engineering AJCSE2014, 1(1):11-17, Sciknow Publications
Ltd. USA.
List of Abbreviations
Mc1
Crushed Aggregate + Sand + 10% OPC
Mc2
Crushed Aggregate + Sand + 12% OPC
Mc3
Crushed Aggregate + Sand + 16% OPC
Mcr1 Crushed Aggregate + Sand + 10% SRPC
Mcr2 Crushed Aggregate + Sand + 12% SRPC
Mcr3 Crushed Aggregate + Sand +16% SRPC
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Table 1. Grain size distributed used for RCC.
Sieve Size (mm)
19
12.5
9.5
4.75
0.6
0.075
% Passing by Weight
98
85
76.5
62.5
26.5
9
Table 2. Details of the design mixes of RCC Samples,Abdullah, 2011.
Moisture
content %
4
5
6
7
8
9
10
11
10
2.167
2.240
2.270
2.330
2.310
2.268
-
Dry Density ( gm. / cm3 )
Cement content %
12
14
16
2.270
2.290
2.320
2.390
2.350
2.355
2.268
2.330
2.346
2.272
2.300
2.320
2.260
2.290
2.240
2.190
18
2.360
2.370
2.320
-
Table 3. Modulus of rupture of freezing and thawing cycles for RCC made of (OPC) and (SRPC).
Mix
Symbol
Mc1
Mc2
Mc3
Mcr1
Mcr2
Mcr3
Modulus of Rupture (MPa)
Number of freezing and thawing cycles
No cycle
30 cycles
60 cycles
6.55
6.16
5.75
7.7
7.41
7.04
8.31
8.1
7.84
7.1
6.88
6.63
7.95
7.72
7.43
9.3
9.2
8.96
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Table 4. Modulus of rupture after alternate freezing and thawing cycles for RCC made of (OPC)
and (SRPC).
Mix
Modulus of Rupture (MPa)
Symbol
Number of wetting and drying cycles
No cycles 30 Cycles
60 Cycles
Mc1
Mc2
Mc3
Mcr1
Mcr2
Mcr3
6.55
7.7
8.31
7.1
7.95
9.3
6.15
7.35
8
6.73
7.64
9.05
5.73
6.98
7.67
6.37
7.31
8.79
Table 5. Modulus of rupture of wetting and drying cycles for RCC made of (OPC) and (SRPC).
Mix symbol Percent decrease after 30 cycles
Percent decrease after 60 cycles
Mc1
6.1
12.5
Mc2
4.5
9.3
Mc3
3.7
7.7
Mcr1
5.2
10.2
Mcr2
3.8
8.0
Mcr3
2.6
5.4
Table 6. Modulus of rupture after alternate wetting and drying cycles for RCC made of (OPC)
and (SRPC).
Mix symbol Percent decrease after 30 cycles Percent decrease after 60 cycles
Mc1
5.9
12.2
Mc2
3.7
8.5
Mc3
2.5
5.6
Mcr1
3.0
6.6
Mcr2
2.8
6.5
Mcr3
1.0
3.6
Table 7. Modulus of rupture of sulfate attack test for RCC made of (OPC) and (SRPC).
Mix symbol Percent decrease after 30 cycles Percent decrease after 60cycles
Mc1
7.7
15.2
Mc2
6.1
12.5
Mc3
5.1
10.5
Mcr1
5.7
11.6
Mcr2
4.1
7.9
Mcr3
3.0
6.3
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Table 8. Modulus of rupture after sulfate attack test for RCC made of (OPC) and (SRPC).
Mix
Modulus of Rupture (MPa)
Symbol Number of freezing and thawing cycles
No cycle
30 cycles
60 cycles
Mc1
6.55
6.16
5.75
Mc2
7.7
7.41
7.04
Mc3
8.31
8.1
7.84
Mcr1
7.1
6.88
6.63
Mcr2
7.95
7.72
7.43
Mcr3
9.3
9.2
8.96
Figure1. RCC mold .
Figure 2. The roller device.
Figure 3. The rolling directions.
Figure 4. The compaction with a roller device.
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Figure 5. Part of RCC slab specimens.
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Journal of Engineering
Figure 6. Part of samples obtained from RCC slab.
Figure 7 . Variation in modulus of rupture with No. of cycle after freezing and thawing for RCC
made of (OPC) and (SRPC).
Figure 8. percentage of decrease in modulus of rupture with cement content for RCC made
of(OPC) and (SRPC) after freezing and thawing cycles.
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Figure 9. Variation in modulus of rupture with No. of cycle after wetting and drying for RCC
made of (OPC) and (SRPC).
Figure 10. percentage of decrease in modulus of rupture with cement content for RCC made of
(OPC) and (SRPC) after wetting and drying cycles.
Figure 11. Variation in modulus of rupture with No. of cycle after sulfate attack test for RCC
made of (OPC) and (SRPC).
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Figure 12 . percentage of decrease in modulus of rupture with cement content for RCC made of
(OPC) and (SRPC) after sulfate attack test.
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A Proposed Management System for Construction Practices during
Sustainable Buildings Life Cycle
Dr. Angham E. Al-Saffar
Zeena Hameed Salman
Professor
Engineering College - Baghdad University
Email:[email protected]
Master Degree
Ministry of Municipalities and Public Work
Email : [email protected]
ABSTRACT
For
many years, the construction industry damages have been overlooked such as
unreasonable consumption of resources in addition to producing a lot of construction waste but
with global awareness growth towards the sustainable development issues, the sustainable
construction practices have been adopted, taking into account the environment and human
safety. The research aims to propose a management system for construction practices which
could be adopted during constructing different types of sustainable buildings besides
formulating flowcharts which clarify the required whole phases of sustainable buildings life
cycle. The research includes two parts: theoretical part which generally ,handles the
sustainability concepts at construction industry and specially buildings .But the practical part
comprises investigating the professional opinions in construction industry about applications
possibility of sustainable requirements and global criteria to construction of sustainable
buildings in Iraq where the weakness and strength points in the essential requirements for
achieving the sustainable construction practices have been diagnosed and the development need
has been specified. The utilized statistical analysis of questionnaire results show readiness of
buildings sectors to implement the sustainable practices. The different strategies and techniques
in the proposed management have been employed for getting the sustainable procedures of
sequences practices within project life cycle.
Key words: system, practices, sustainable buildings, phases.
‫وظام إداري مقترح للتطبيقاث االوشائيت خالل دورة حياة المباوي المستذامت‬
‫زيىت حميذ سلمان‬
‫دسخت انًبخستُش‬
‫وصاسة انبهذَبث واالشغبل انؼبيت‬
‫ أوغام عس الذيه الصفار‬.‫د‬
‫استبر‬
‫كهُت انهُذست – خبيؼت بغذاد‬
‫الخالصت‬
‫ تى اغفبل اضشاس انظُبػت االَشبئُت كبالستهالن اناليؼمىل نهًىاسد فضال ػٍ اَتبج انكثُش يٍ انًخهفبث‬, ‫خالل سُىاث ػذَذة‬
ٍ‫ نكٍ يغ تُبيٍ انىػٍ انؼبنًٍ َسى لضبَب انتًُُت انًستذايت تى تبٍُ فؼبنُبث اَشبئُت يستذايت (تطبُمبث) تبخز ف‬, ‫االَشبئُت‬
‫ َهذف انبسث انً التشاذ َظبو اداسٌ نهفؼبنُبث االَشبئُت ًَكٍ إػتًبدِ خالل إَشبء اَىاع يختهفت‬.ٌ‫انسسببٌ ساليت انبُئت واألَسب‬
ٍَ‫يٍ االبُُت انًستذايت انً خبَب طُبغت يخططبث اَسُببُت تىضر األخشاءاث انًطهىبت نكبفت يشازم دوسة زُبة انًبب‬
‫ زُث تُبول يفبهُى األستذايت فٍ انظُبػت األَشبئُت بشكم ػبو‬, ٌ‫ اندضء انُظش‬: ٍُُ‫ تضًٍ انبسث خضئٍُ أسبس‬. ‫انًستذايت‬
‫وانًببٍَ بشكم خبص وأيب اندضء انؼًهٍ فشًم أستطالع أساء انًختظٍُ فٍ انظُبػت األَشبئُت زىل إيكبَُت تطبُك يتطهببث‬
‫ويؼبَُش األستذايت انؼبنًُت فٍ إَشبء انًببٍَ انًستذايت فٍ انؼشاق زُث تى تشخُض َمبط انمىة وانضؼف فٍ تطبُك انًتطهببث‬
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ٌ‫اظهش انتسهُم االزظبئٍ انًستخذو نُتبئح األستبُب‬. ‫انالصيت نتسمُك انفؼبنُبث األَشبئُت انًستذايت وتسذَذ يذي انسبخت نهتطىَش‬
‫ وتى تىظُف استشاتُدُبث وتمُُبث يختهفت فٍ انُظبو االداسٌ انًمتشذ‬. ‫استؼذاد لطبع االبُُت نتُفُز يتطهببث انفؼبنُبث انًستذايت‬
‫إػتًبدا ػهً يؼبَُش تمُُى انًببٍَ انًستذايت نهسظىل ػهً أسبنُب إخشائُت يستذايت نهفؼبنُبث انًتتبنُت ضًٍ دوسة زُبة‬
. ‫انًششوع‬
1 - INTRODUCTION
The present global environmental conditions are consequence of the increasing consumption of
natural resources whose depletion exceeds what is physically possible to sustain in the long
term. The effects resulting in damage of eco-systems are very evident. Therefore the need arises
to find clean friendly sources for energy with environment and other strategies for protecting
both of the environment and the opportunities of next generation for sharing with these
resources within sustainability frame.
The construction sector is complex and has, therefore, a tendency to resist changes
towards sustainability. Designers and project managers are facing barriers to the application of
sustainability, e.g. lack of pro-active sustainable measures, conflicts in real and perceived costs
and inadequate implementation expertise.
The sustainable construction practices are modern subject and the sustainable construction
captures interesting position of the researchers but until now there is no management system for
sustainable construction practices. In this research the researcher will propose management
system for managing them during sustainable buildings life cycle therefore this research is
considered the first thesis interested in this subject. The research scope of the sustainable
buildings includes commercial buildings, public services (non-housing) buildings, multiresidential buildings and managerial buildings.
2- SUSTAINABLE CONSTRUCTION
The goals of sustainable construction are to maximize resource efficiency and minimize waste in
the building assembly, operation, and disposal processes. Sustainable construction seeks to
dovetail the construction industry into the global sustainable development movement by moving
it onto a path where it adheres to principles that are able to provide a good quality of life for
future generations , Panagiotakopoulos,2005.
2-1 Management of Sustainable Construction
The management team of a sustainable construction work project should consider the entire
process from an early design stage towards the final product, and the benefits and negative
impacts regarding the triple bottom-lines of sustainability that are to be expected during the
lifetime of the final product, i.e. the facility , Persson , 2009.
2-2 The Sustainable Construction Practices
Sustainable construction practice refers to various methods in the process of implementing
construction projects that involve less harm to the environment - i.e. prevention of waste
production, increased reuse of waste in the production of construction material - i.e. waste
management, beneficial to the society, and profitable to the company ,Akadiri , 2011. To create
a competitive advantage using environment-friendly construction practices and the whole lifecycle of buildings should be adopted also, Akadiri et al., 2012.
3- LIFE CYCLE OF SUSTAINABLE BUILDING
The term “Sustainable buildings” is often used interchangeably with “green buildings” or “ecobuildings” ,ADUPC,2010. Construction activities affect the environment throughout the life
cycle of a construction project. This life-cycle concept refers to all activities from extraction of
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resources through product manufacture and use and final disposal or recycle, i.e. from “cradle to
grave” , Akadiri, 2011.
The Whole Building Life-Cycle that guides current practices comprises processes of
feasibility ,design, construction, operation, renovation, and demolition of buildings
,Panagiotakopoulos,2005, Randolph et al., 2008, and Mer'eb, 2008. Bauer et al.,2010,
attempted to extend this thinking even further by considering the regenerative and productive
reuse of products and materials in what they call a “cradle-to- cradle” approach.
As a result of advance, the researcher supposes the sustainable buildings life cycle should
include the phases: planning, design, procurement, implementation, operation and maintenance,
post operation and maintenance (which could include deconstruction / reusing / disposal/
demolition).
3-1 Cost of Sustainable Buildings
The opinions about the cost of sustainable buildings are divided into three attitudes:
1) Halliday, 2008, refers the overriding assumption that sustainable building inevitably costs
more or is less profitable based on the market-driven economies and doesn‟t adopt them besides
the innovation required has a cost implication of time, planning, risk and enhanced information
requirements, and the innovators will be penalized and their profit margins reduced when put in
direct competition with unsustainable practices.
2) Persson , 2009, opposes ,Halliday, 2008, by saying "there is a common misunderstanding
that sustainability in construction works is more expensive in terms of investment costs
compared to „normal‟ mainstream buildings.", based on survey conducted by the World
Business Council for Sustainable Development in 2008 which investigated the difference in
investment cost between a „normal‟ building and a certified sustainable building which is about
17% for the last and ,Persson , 2009,added that the initial costs do not necessarily increase if
energy consumption (one of the most significant factors in building sustainability) is reduced by
about 50%.
3) Myers, 2008, takes the neutral side when he clarified that cost-benefit analysis is a way of
appraising an investment proposal. It involves taking into account the external costs and benefits
of a proposed development as well as the conventional private costs and benefits. This is done
by estimating monetary values for aspects such as health, time, and pollution.
3-2 Tools of Sustainable Buildings Projects Management
The researcher notes some tools are used numerously in management of sustainable buildings
projects which are:
1) Life-cycle cost analysis
Life-cycle cost - sometimes also called - Whole-Life Cost (WLC) is the assessment of all
relevant costs and revenues associated with a building over an agreed period, including
procurement, operation and sometimes disposal. Whole-life cost looks at the life cycle from the
start of design and construction, and might include: procurement costs, operating costs,
recurring, end-of-life and revenue ,Halliday, 2008.
2) Value engineering
In sustainable perspective, in value engineering all alternatives can be compared using life-cycle
costing because the alternatives for each project component (systems, materials, plant, and
processes) are defined to satisfy the same basic function or set of functions. When the
alternatives all satisfy the required function, then the best value alternative can be identified by
comparing the first costs and life-cycle costs of each alternative for achieving lowest life-cycle
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cost consistent with the required performance. Value engineering has been used at sustainability
issues as siting factor, energy issues, water, facility costs ,Federal Facilities Council, 2001.
3) Computer simulation
During the planning and construction process, computer-based simulation programs are used
,Bauer et al., 2010. Site and Project Planning Group, 2002, showed that computer simulation
is used at pre-design, schematic design, design development, construction, commissioning, postoccupancy. Computer simulations serve to define the following practices ,Bauer et al., 2010:
a. Maximum and minimum air temperature settings or indoor heating and/or cooling load, for
thermal indoor comfort.
b. The operating behavior of a given building under real-life and variable conditions for
defining energy efficiency.
c. For evaluation and optimization of a building and its envelope.
d. Using most efficiency water strategies.
4) Rating systems
Rating systems have been developed to measure the sustainability level of green buildings and
provide best-practice experience in their highest certification level. With benchmarks, the
design, construction and operation of sustainable buildings will be certified using several criteria
,Bauer et al., 2010.
It is important to realize that any scheme is very good mechanism for encouraging design
teams, particularly those unfamiliar with the issues of sustainable design, to focus on a client
aspiration ,Halliday, 2008.These systems often provide a defined format for projects to compare
to a baseline to determine how they measure up against other projects , Sarté, 2010.
The researcher could draw out some of the most criteria repeatedly, which could search
within the following axes: sustainable site, water efficiency, energy and atmosphere, materials
and resources, indoor environmental quality and innovation in design.
4- MANAGEMENT OF CONSTRUCTION PRACTICES DURING SUSTAINABLE
BUILDINGS LIFE CYCLE
The ways of management the sustainable construction practices could be explored and
categorized them during sustainable buildings life cycle phases as follows:
4-1 Planning phase
Every project starts with a vision and a set of objectives. Once the structure is agreed on, a
project has been defined and agreed upon, the next step is to establish appropriate design
strategies to meet those goals ,Sarté, 2010. Planning initiate with feasibility study which is
carried out by assessing the client‟s objectives and providing advice and expertise in order to
help the client define more precisely what is needed and how it can be achieved ,The Chartered
Institute of Building, 2002.
Federal Facilities Council, 2001, states that ecologically and culturally sensitive areas
should be considered at sustainable site planning. The cost plays essential role in water planning
.For example, in the tertiary treatment levels, they have improved water quality but they have
come at a high energy cost ,Sarté, 2010.
USGBC, 2009, states that the requirements like on-site renewable energy self-supply,
minimum and optimize energy performance, measurement and verification should be considered
at this phase.
In selecting sustainable materials, designers should aim to maximize durability, energy
efficiency, recyclability, maintainability, and use of local materials to minimize the use of
hazardous materials, and synthetic chemicals by using a strategy in the choice ,Akadiri ,2011.
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Life-cycle assessment (LCA)could be used as a method to measure and evaluate the
environmental burdens associated with a product system or activity, by describing and assessing
the energy and materials used and released to the environment over the life cycle ,Halliday,
2008.
The planning phase, must take into account outdoor air quality levels, all the possibilities
and limits of air supply in respect to natural ventilation via the windows, filtering and cleaning
of outdoor air ,Bauer et al., 2010. Besides using passive cooling strategies, it includes
,Halliday, 2008.
4-2 Design Phase
Green buildings incorporate three critical factors: energy, environment /ecology, and human
health. These factors are keys to the design process ,Panawek, 2007. In sustainable site design
the land, its hydrology, and the complex diversity of living systems are interdependent and
cannot be isolated from the design process, Sarté, 2010.
Site design begins with the analysis of the site and environmental conditions and integrates
them into the program and design solution. Integrating the natural attributes of the site can
reduce energy consumption considerably ,Williams, 2007.
Federal Facilities Council, 2001, considers the following issues:
1) Specifying measures of water use can be taken to ensure is as efficient as possible.
2) Specifying measures to reduce, control, and treat surface runoff.
3) Incorporating rainwater collection cisterns and separate gray water systems for belowground irrigation to eliminate the use of potable water.
Designers can therefore help reduce operational energy consumption of buildings by
adopting designs that reduce heat losses through the building envelop, reduce cooling and
heating loads and by introduction of energy saving measures ,Ndungu , 2008.
The efficient utilization of resources as possible needs to specify the use of renewable and
recycled sources in order to close the life-cycle loop of materials and select materials with the
least environmental impact throughout their entire lifetime Akadiri ,2011.
Design of indoor environment considers the following ,Bauer et al., 2010:
1) Assuring optimal air quality.
2) The amount of daylight reaching the room.
3) The solar protective device‟s automation.
4-3 Procurement Phase
Federal Facilities Council, 2001, states that the following should be considered at procurement
phase:
1) Stipulation on specification design criteria.
2) The contract method that will best support the achievement of sustainability objectives.
3) Implications of the choice of project delivery method.
4) Implications of the contract selection procedure.
5) The types of incentives and clauses.
6) Types of evaluations used.
7) The side responsible for sustainable construction practices.
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8) The required level of commissioning, the liability for failures to meet the requirements and
the remediation method in the failures case.
4-4 Implementation Phase
Implementation stage is the actual execution of what has been planned to be a development
project. Implementation is made according to projects agreement and memorandum. During the
implementation process complexity and risks come to closer, bureaucratic problems, and
conflicts could emerge ,Oyoko et al., 2008.
Halliday, 2008, mentions that particular attention should be paid to the commissioning
operations – not just of innovative technology. Checking that products are of the required
quality and that they work as specified is essential. It will become clear at this point how
important it is to specify all the testing regimes at the tender period.
The following the procedures could be taken in the construction phase ,Federal Facilities
Council, 2001:
1) Evaluation, analysis, and consideration of change orders that may affect facility
sustainability.
2) Study on value engineering of change proposals.
3) Implementation of monitoring procedures.
4) Reduction or elimination of the production of harmful waste.
5) Protection of construction workers from the hazard waste.
4-5 The Occupancy (Operation and Maintenance) Phase
The constructed works are expected to be in service for a long time. Maintenance is defined,
according to Standard of International Organization for Standardization (ISO 15686-1), as:
“Combination of all technical and associated administrative actions during service life to retain
a building or its parts in a state in which it can perform its required functions” ,Hallberg ,
2005.
The most important job in maintenance is to make regular checks which might betray a
more serious durability threat. Simple visual checking is often all that is required, but it should
be thorough and regular. In this way almost all serious problems can be spotted early and dealt
with cheaply and simpl, Halliday ,2008.
4-6 Post Operation and Maintenance Phase
At the end of life phase, sustainability issues that need to be considered are the reduction of
waste when the buildings are demolished. All avenues to recover materials by recycling and
reuse should be explored ,Ndungu, 2008. Accordingly the researcher handled the following
aspect:
1) Deconstruction
The processes of dismantling a building or site have shifted from demolition to deconstruction
,Calkins, 2009. Deconstructing a building is the careful dismantling of that building so as to
make possible the recovery of construction materials and components, promoting their reuse and
recycling ,Couto et al., 2010. A good deconstruction contractor will be able to reclaim/recycle
75%–95% of the site and building if salvage or recycling markets are available nearby ,Calkins,
2009.
2) Source-separated recycling
Source-separated recycling (also called source separation) is the alternative to commingling. The
highest benefits of recycling come from separating waste materials at the jobsite , transporting
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and recycling them individually into a different container which is then transported by a
recycler, transfer site, or directly to individual markets ,Chiras, 2006.
3) Reclaiming and reusing of materials and products
Reusing materials can add a layer of meaning to a project, revealing the cultural history of a
place, which is often difficult to achieve with mass production due to the following ,Calkins
,2009:
a. Finding appropriate types and quantities of materials.
b. There is often additional design time.
c. A reclaimed material will not be found in a catalog with all specifications listed.
4) Demolition
The demolition reduces the building or site to debris without preserving the integrity of its
components for reuse ,Calkins, 2009. During the demolition, rubble and debris are hauled away
and disposed into the sea and sometimes at abandoned quarries ,Ndungu, 2008.
5- FIELD SURVEY
There is a common misunderstanding supposes that the sustainable construction of the buildings
is more expensive in terms of investment costs compared to traditional buildings and adoption of
sustainable construction in construction works will lead to delay or confusion in methodology.
Therefore, proposing a management system for the construction practices during sustainable
buildings life cycle aims to correct this misunderstanding and encourage adoption of the
sustainable construction practices and solve the avoidance of sustainable buildings.
As a result, the researcher embarked in testing the research hypothesis through field
survey .The field investigation passed two stages, as follows:
1-Open questionnaire stage: through personal interview.
2-Closed questionnaire stage: by using questionnaire form.
The closed questionnaire form includes investigation the requirements of sustainable
construction practices through six axes of sustainability: site, water efficiency, energy
efficiency, and indoor environmental quality, innovation in design and awareness and education.
Four determinants facing application the requirements of sustainable construction practices have
been used in survey which is application's possibility, difficulty types, influence on cost and
influence on time. The results of the first two determinates have been discussed depending on
frequency distribution but the last two determinates have been discussed depending on the
evaluation of statistical analysis results.
5-1 Statistical Analysis
The statistical analysis is used for analyzing the closed questionnaire results related with
participants responses to the two determinants of using axes requirements which concern
requirement influence on cost and on time by considering each response type of (always, often,
some times and no) a class could give it evaluation range and extraction the class evaluation of
degree (class center) as clarified in Table 1.The researcher used the following statistical
features:
First: – The arithmetic mean
The weighted mean is used to evaluation every requirement of questionnaire axes .It has been
calculated from the following equation ,Moore et al., 2009:
M= ∑
(1)
where:
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M = Responses weighted mean about requirement influence on cost or time.
Xi =Evaluation degree of responses class (i) about requirement influence on cost or time.
Fi = Responses frequency for class (i) about requirement influence on cost or time.
N= Sample size in each requirement.
The above equation is applied to influence of every requirement on each the cost and time.
Second: – The conformance ratio
It is used in influence evaluation for every axis of questionnaire axes on the cost and time .It
represents congruence extent of axis influence with the ideal status depending on responses
frequency for sample individuals by applying the following equation ,Al- Ani, 2006:
Cr = M / Xmax
(2)
Where:
Cr = Axis conformance ratio.
M = Arithmetic mean of responses weighted mean.
Xmax= The maximum evaluation degree which represents the maximum class center for the
responses evaluation (8.75).
The analysis and evaluation of the questionnaire results for every axis of questionnaire
axes depend on conformance ratio computed for every axis whose value varies from (1.25/8.75 1) where the median of these ratios is the average of (0.42) and (0.72) and equals (0.57) and it is
considered the lower limit to axis analysis, then the upper quartile will be computed for the
values (0.14-1) as follows:
a- If (Cr < 0.57), then evaluation of axis influence is (poor) therefore the required development
would be (must).
b- If (0.57≤ Cr ≤ 0.86), then evaluation of axis influence is (accepted-middle) therefore the
required development would be (wanted).
c- If (Cr > 0.86), then axis evaluation is (good-very good) therefore the required development
would be (desired).
Based on results of total weighted mean listed in Table 2, all axes have Cr < 0.86 thus all
axes affect cost and time therefore the supposed actions which make the axes affect cost and
time need development. Also from Fig. 1, it could be noted there is relation between the axis
influence on cost and time since whenever the axis affect cost, it affect time too.
As a conclusion from analysis the closed questionnaire results, the building construction
sector has the readiness for inclusion of the sustainability aspects but it suffers from absence of
management system because of some of difficulties which are summarized by technical
difficulties in the first place, followed by managerial difficulties are due to lack of awareness of
sustainability targets in addition fear of effect on cost and time of project if the sustainable
construction practices have been applied. But the proposed actions of management system could
overcome both lack of awareness and some of these effects.
Then the comprehensive view of extent of acceptance of building construction sector has
been reached .In addition, the light is shed on fields that need to be developed .Based on the
results, the researcher could diagnose the weaknesses and strengths in managing the sustainable
construction practices.
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6- THE PROPOSED MANAGEMENT SYSTEM OF SUSTAINABLE BUILDINGS
The management system is an approach used to organize the activities and the resources to
perform the actions according to a specified cost and time program relating to certain objectives.
Since sustainable building life cycle consists of six phases, previously mentioned, the researcher
has tracked the construction practices through the sustainability aspects during life cycle phases
to find out the procedures and at the end to formulate the proposed management system.
The proposed management actions are based on management strategies and techniques
that constitute most difficulties facing the construction practices, as well as the cost and time
management through the placed plans and requirements that precede the intended actions, where
every criterion of sustainable site, water efficiency, energy and atmosphere, materials and
resources, indoor environmental quality, and innovation in design comprise many construction
practices.
6-1 The Proposed Planning Actions for Sustainable Buildings
The planning phase is considered the first phase in the project. The project –owner requirements
should be defined to clarify the project scope by the planning consultant and the project team
(project manager, engineers, geotechnical specialists, other specialists, land surveyors, cost
estimator and quantity surveyors etc.). At this point the sustainability features begin to originate
from environmental and sustainability objectives such as energy targets, the systems
performance requirements, operation and maintenance, occupants' requirements, owner and user
requirements that are stipulated in project –owner requirements document as shown in Fig. 2.
Fig. 2 shows the main planning actions for sustainable buildings including the following:
1- Establishing the sustainability vision, objectives, and measurements and implementing
systems approach.
2- Feasibility study and cost estimations
3- Site selection
4- Value engineering
5- Schematic design
6- Developing the basis of design (BOD)
7- Cost efficiency management system
6-2 The Proposed Design Actions for Sustainable Buildings
For advancing sustainability in design, the following could be achieved:
1- Integrate sustainability vision and values into design.
2- Implement sustainability objectives, measurement system, systems thinking models and
sustainability framework.
3- Implement sustainability approaches.
4- Applying Life cycle assessment for sustainability features.
As shown in Fig. 3, for conversion to sustainable design the sustainability axes such as
sustainable site, water efficiency, energy and atmosphere, material and resources and indoor
environmental quality, and innovation in design have been considered. Each of these axes
includes more than design set. Fig. 3 shows actions that should be followed in each axis and
how the researcher employed the construction practices related to them in the design phase.
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6-3 The Proposed Procurement Actions for Sustainable Buildings
The procurement in construction life cycle of sustainable buildings is related to purchasing of
materials, plant, and the correct choice of suppliers and subcontractors. The actions related to
procurement could include the following:
1- Integrate sustainability vision and values into procurement.
2- Implement sustainability objectives, measurement system, systems models and sustainability
framework.
3- Commit to green purchasing policy.
4- Implement sustainability.
5- Engaging procurement in design for a sustainable supply chain
As a result, the researcher summarized the procurement actions in a proposed flowchart in
Fig. 4.
6-4 The Proposed Implementation Actions for Sustainable Buildings
The following activities must be followed:
1- Integrate sustainability vision and values into construction.
2- Implement sustainability objectives, measurement system, and sustainability framework.
3- Implement sustainability approaches.
4- Manage and minimize CO2 emissions in construction.
Fig. 5 describes actions which must be undertaken for managing the implementation of
sustainable buildings which are characterized by performing all the previously arranged plans
starting from performing time management and ending in performing operation and handover
plan.
The most time-consuming activity in the project is the creation of the physical
constructing of practices. Fig. 6 explains the work mechanism that is followed in
implementation according to sustainability axes. It is obvious from Fig. 6 focusing on testing
efficiency of all of the installed systems and sustainable practices insures of achieving the cost
saving at its performing and environmental targets that are planned before. Many of the
management process have been permeated and schemed at the planning phase.
6-5 The Proposed Operation and Maintenance /Occupancy Actions for Sustainable
Buildings
The suggested operation and maintenance actions are as follows:
1- Integrate sustainability vision and values into operation and maintenance stage.
2- Implement sustainability objectives and measurement system.
3- Start early in planning and design to provide operation and maintenance input to project
development.
4- Implement sustainability approaches.
5- Individual behaviors and individual ownership
This phase is very important in achieving the planned and designed savings therefore it
should be of interest. As a result the researcher suggests the flowchart in Fig. 7 for the operation
and maintenance actions.
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After operational building life has been finished, the structural element should be
sustained through reusing of them at the same site and rehabilitation the capable elements by
friendly–environmental materials
6-6 The Proposed Post-Operation and Maintenance Actions for Sustainable Buildings
The sustainability's tendency doesn‟t end with building occupancy and benefits harvested that
had been looked forward but this stage could be exploited to service the building's sustainability
in materials arena ,through construction waste management including reusing, recycling
,reprocessing and safety disposal.
Fig. 8 represents the proposed actions for post-operation and maintenance that the
researcher proposes where advanced planning for deconstruction or salvage before demolition is
crucial for its success.
Building deconstruction supports the waste management in its sequence of preferred
options for the management of generated waste materials. If a building is still structurally sound,
durable and flexible enough to be adapted for a different use, then waste can be reduced by
reusing the whole building. If components and materials of a building can be recovered in high
quality condition, then they can be reused. If the building materials are not immediately
reusable, they can be used as secondary feedstock in the manufacture of other products, i.e.,
recycled. The aim is to ensure that the amount of waste that is destined for landfill is reduced to
an absolute minimum. This approach closes the loop in material flow thereby contributing to
resource efficiency.
At last, the proposed management system flowchart during sustainable buildings life cycle
is summarized as shown in Fig. 9.
7- CONCLUSIONS
1. As a result of undertaking closed questionnaire, it was determined there was awareness lack
about realizing the benefits of a sustainable approach in construction in Iraq which has led to
absence of sustainable construction practices.
2. There is a huge lack in understanding the techniques of sustainable construction.
3. There is a relationship between some sustainable construction practices therefore application
some of them will be reflected positively or negatively on other practices whether in direct or
indirect way.
4. When the aim is to reduce site pollution, achieve indoor environment quality, reduce using
the materials and resources this really leads to additional costs but on other hand the increase in
cost could be balanced by the efficient use of materials and resources in construction phase,
operation and maintenance phase and in the next-phase, moreover efficient use of water, energy
at operation phase could save cost too.
5. Although application of the management system of sustainable construction practices may
increase initial costs of buildings through design and construction phase, it will lead to cost
savings greater than initial investment besides the environmental and social benefits. These
savings are due to reduced water costs, lowered energy use, lowered, and decreased waste
disposal, reduced operation and maintenance costs, and savings resulting from increasing
productivity.
6. Some of sustainable construction practices affect time but as noted in the proposed
management system more than sustainable practice can be applied at the same time with each
other in addition to traditional practice as a result time as possible as could be saved.
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7. Adopting the sustainability principles, especially at the post-operation and maintenance
phase (deconstruction /disposal), could help in providing work opportunities and reduce the
unemployment.
8- RECOMMENDATIONS
The following recommendations have been drawn to enhance the proposed management system
for sustainable construction practices:
1.
Applying the proposed management system in all details and actions to the future
sustainable buildings projects in Iraq.
2. It should be of interest to develop the current techniques in construction practices in Iraq to
be sustainable.
3. It is necessary to make the competition basis between the constructed company according to
its commitments about implementing the sustainability's' principles by introducing the related
plans within the bid.
4. Holding training courses and workshops to spread the sustainability aspects for both private
and public sectors in collaboration with professionals who have experience in construction
sustainability from abroad that are very advanced at this arena.
5. Establishing Iraqi sustainable buildings council which will be in charge of rating the
sustainable buildings projects and giving recognized certification for this purpose as well as
issuing guides for specifying the sustainable buildings similar to what is done in other countries
like Abu Dhabi, USA, and Australia etc..
REFERENCES
ADUPC., 2010, The PEARL Rating System For ESTIDAMA: Building Rating System for Design
and Construction, Version 1.0, Abu Dhabi Urban Planning Council, U.A.E.
Akadiri ,P. O. ,2011, Development of A Multi- Criteria Approach for The Selection of
Sustainable Materials for Building Projects, Ph.D. Thesis, Wolverhampton University.
Akadiri, P. O. ,Chinyio , E. A. ,and Olomolaiya , P. O. ,2012, Design of a Sustainable Building:
A Conceptual Framework for Implementing Sustainability in the Building Sector,An Article,
Journal of Buildings, Vol.2, May 4, pp.126-152.
Al- Ani, Raad D. N. ,2006. Development of Construction Designs Quality Assurance Program
For Building Projects, A M.Sc. Thesis, Civil Engineering Department, Al-Mustansiriya
University.
Bauer, M., Mӧsle , P., and Schwarz, M. ,2010, Green Building: Guidebook for Sustainable
Architecture, Springer, Germany.
Calkins, M. ,2009, Materials For Sustainable Sites: A Complete Guide to the Evaluation,
Selection, And Use Of Sustainable Construction Materials, John Wiley& Sons, New Jersey.
Chiras, D. ,2006, The Homeowner's Guide to Renewable Energy: Achieving Energy
Independence through Solar, Wind, Biomass and Hydropower, New Society Publishers, Canada.
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Couto,J. And Couto,A.,2010, Analysis Of Barriers And The Potential For Exploration Of
Deconstruction Techniques In Portuguese Construction Sites,A Review, Journal Of
Sustainability, Vol.2, January 27, pp.428-442.
Federal Facilities Council ,2001, Sustainable Federal Facilities: A Guide To Integrating Value
Engineering, Life-Cycle Costing, And Sustainable Development, A Technical Report No.142,
National Academy Press, Washington.
Hallberg, D. ,2005,Development And Adoption Of A Life Cycle Management System For
Constructed Works, M.Sc. Thesis, KTH Architecture and Built Environment College, University
of Gӓlve, Sweden.
Halliday, S. ,2008, Sustainable Construction, First Edition, Elsevier, Slovenia.
Mer'eb, M. M. ,2008, GREENOMETER-7: A Tool To Assess The Sustainability Of A Building's
Life Cycle At The Conceptual Design Phase , Ph.D. Thesis, Cleveland State University.
Moore, D. S. and Notz W. I. ,2009, Statistics: Concepts And Controversie,Seventh Edition,
Freeman And Company, New York.
Myers, D. ,2008, Construction Economics: A New Approach, Second Edition, Taylor & Francis
Group, USA.
Ndungu, P. ,2008, Sustainable Construction: Comparison Of Environmental Impact Due To OffSite Vs. On-Site Construction, M.Sc. Thesis, College of Engineering, University of Cincinnati.
Okoyo, M., Hussein, M. ,2008, Swedish Aid Policy And Development Projects In Kenya: An
Analysis Of Strategy And Organization, M.Sc. Thesis, School of Sustainable Development of
Society and Technology, University of MӒLARDALEN.
Panagiotakopoulos, D. P. ,2005, A System And Cybernetics Approach To Corporate
Sustainability In Construction , Ph.D. Thesis, School of Built Environment, Heriot – Wat
University, Edinburgh.
Panawek, K. ,2007, Changing „Light‟ Green to „Deep‟ Green: Mainstreaming Green Building
In Hamilton County: An Analysis & Evaluation Of The Constraints Facing The Green Building
Housing Market In Hamilton County, M.Sc. Thesis, College of Design, Architecture, Art and
Planning, University of Cincinnati.
Persson, U. ,2009, Management Of Sustainability In Construction Works, Ph.D. Thesis,
Division Of Construction Management, Lund University, Sweden.
Randolph, J. And Masters, M. G. ,2008, Energy For Sustainability: Technology, Planning,
Policy ,Island Press, Washington.
Sarté, S. B. ,2010, Sustainable Infrastructure: The Guide To Green Engineering And Design ,
John Wiley& Sons, New Jersey.
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Site and Project Planning Group. ,2002, LANL Sustainable Design Guide, LANL, New Mexico,
United States.
The Chartered Institute of Building. ,2002, Code Of Practice For Project Management For
Construction And Development, Third Edition, Blackwell, UK.
USGBC. ,2009, LEED 2009 For New Construction And Major Renovations,USGBC,
Washington.
Williams, E. D. ,2007, Sustainable Design: Ecology, Architecture, And Planning ,John Wiley&
Sons, New Jersey.
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Table 1. Distribution evaluation degree on responses classes.
Response Class
Evaluation Range
Evaluation Degree
No
Sometimes
Often
Always
(10 - 7.51)
(7.5 - 5.1)
(5 - 2.51)
(2.5 - 0)
8.75
6.3
3.75
1.25
Axis
Conformance
Ratio (Cost)
Evaluation of
Axis Influence
Development
of Supposed
Axis Actions
Evaluation of
Axis Influence
Development
of Supposed
Axis Actions
Site
67.39
0.59
acceptedmiddle
wanted
73.18
0.64
acceptedmiddle
wanted
21.33
0.49
poor
must
24.32
0.56
poor
must
19.77
0.45
poor
must
23.82
0.54
poor
must
Water
Efficiency
Power and
Atmosphere
Total
Weighted
Mean
Axis
Conformance
Ratio (Time)
Axis
Total
Weighted
Mean
Table 2. The evaluation of influence of axes on cost and time compared with ideal condition.
(Researcher)
Axis Influence on Cost
Axis Influence on Time
Table 2. continued.
Axis Influence on Cost
Development
of Supposed
Axis Actions
Evaluation of
Axis Influence
Development
of Supposed
Axis Actions
55.00
0.63
acceptedmiddle
wanted
59.30
0.68
acceptedmiddle
wanted
73.46
0.60
acceptedmiddle
wanted
84.54
0.69
acceptedmiddle
wanted
23.36
0.67
wanted
25.11
0.72
17.77
0.68
wanted
19.92
0.76
acceptedmiddle
acceptedmiddle
29
Total
Weighted
Mean
Axis
Conformance
Ratio (Time)
Evaluation of
Axis Influence
Innovation in
Design
Awareness and
Education
Axis
Conformance
Ratio (Cost)
Materials and
Resources
Indoor
Environmental
Quality
Total
Weighted
Mean
Axis
Axis Influence on Time
acceptedmiddle
acceptedmiddle
wanted
wanted
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Figure 1. Conformance ratio of axis influence on cost and time compared with ideal condition.
Figure 2. The proposed planning actions flowchart (researcher).
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Figure 3. The proposed design actions flowchart (researcher).
Figure 4. The proposed procurement actions flowchart (researcher).
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Figure 5. The proposed implementation actions flowchart (researcher).
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Figure 6. The proposed work mechanism in implementation phase of sustainable
buildings (researcher).
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Figure 7. The proposed actions of operation and maintenance for sustainable buildings
(researcher).
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Figure 8. The proposed actions of post-operation and maintenance for sustainable buildings
(researcher).
Figure 9. Summary of the proposed management system flowchart during sustainable
buildings life cycle (researcher).
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Design and Implementation of ICT-Based Recycle-Rewarding System for Green
Environment
Dr. Mohammed Issam Younis
Department of Computer Engineering
College of Engineering / University of Baghdad
[email protected]
ABSTRACT
T
his paper proposes a collaborative system called Recycle Rewarding System
(RRS), and focuses on the aspect of using information communication technology (ICT) as a
tool to promote greening. The idea behind RRS is to encourage recycling collectors by paying
them for earning points. In doing so, both the industries and individuals reap the economical
benefits of such system. Finally, and more importantly, the system intends to achieve a green
environment for the Earth. This paper discusses the design and implementation of the RRS,
involves: the architectural design, selection of components, and implementation issues. Five
modules are used to construct the system, namely: database, data entry, points collecting and
recording, points rewarding, and web modules. The RRS has been deployed at the Universiti
Sains Malaysia (USM) to encourage the collectors to support the green environment.
Keywords: RFID, recycling, information engineering, software engineering, ICT.
‫تصوين وتنفيذ نظبم الاعبة التدوير والوكبفأ للبيئة الخضراء الوستند اعلى تكنولوجيب الوعلوهبت‬
‫واالتصبالت‬
‫ هحود اعصبم يونس‬.‫ة‬.‫م‬
‫قسى هُذسخ انحبسجبد‬
‫ جبيعخ ثغذاد‬/ ‫كهٍخ انهُذسخ‬
‫الخالصة‬
‫ وٌشكز عهى جبَت اسزخذاو‬,‫ٌقزشح هزا انجحث رصًٍى ورُفٍز َظبو رعبوًَ يحىست العبدح انزذوٌش وانًكبفأح نهجٍئخ انخضشاء‬
‫ انفكشح وساء هزا انُظبو هً رشجٍع جبيعً انًىاد انقبثهخ‬.‫ركُىنىجٍب انًعهىيبد واالرصبالد كأداح نزعزٌز رخضٍش األسض‬
ًُ‫ فإٌ كال يٍ انًصبَع واألفشاد رج‬،‫ وثزنك‬. ‫ ويٍ ثى دفع أجىس يقبثهخ نهُقبط انًكزسجخ‬,‫نهزذوٌش عٍ طشٌق احزسبة َقبط نهى‬
‫ رُبقش هزِ انىسقخ رصًٍى ورُفٍز انُظبو‬.‫ َحقق انجٍئخ انخضشاء نألسض‬,‫ واألهى يٍ رنك‬.‫فىائذ اقزصبدٌخ يٍ هزا انُظبو‬
‫ ٌقزشح انجحث خًسخ وحذاد‬,‫ فضال عٍ رنك‬. ‫ وقضبٌب انزُفٍز‬،‫ واخزٍبس انًكىَبد‬،‫انزصًٍى انًعًبسي‬: ًٍ‫ ورزض‬،‫انًقزشح‬
‫ ووحذح شجكخ‬،‫ وحذح يكبفأح انُقبط‬,‫ وحذح جًع ورسجٍم انُقبط‬، ‫ وحذح إدخبل انجٍبَبد‬،‫قبعذح انجٍبَبد‬: ً‫ وه‬،‫نزشٍٍذ انُظبو‬
.‫ وقذ رى وضع انُظبو انًقزشح حٍز انزطجٍق فً جبيعخ انسبٌُس انًبنٍزٌخ نذعى انجٍئخ انخضشاء‬.‫اإلَزشَذ‬
‫ ركُىنىجٍب‬،‫ هُذسخ انجشيجٍبد‬،‫ هُذسخ انًعهىيبد‬،‫ انزذوٌش‬,‫رحذٌذ انهىٌخ ثبسزعًبل انًىجبد انشادٌىٌخ‬: ‫الكلوبت الرئيسية‬
.‫انًعهىيبد واالرصبالد‬
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1. INTRODUCTION
During the past decade, radio frequency identification (RFID) systems have been incorporated
into a wide range of industrial and commercial systems, Chen, et al., 2010. Its low cost
provides a wide spectrum of applications that have never been seen in literature, Akyildiz, et al.,
2002. RFID is a form of automatic contactless data capturing technique that uses radio
frequency electromagnetic waves. An RFID system is comprised of a transponder (tag), a
reader, and a host computer (software application), which is usually connected to a distributed
database. The readers are usually placed in certain places to recognize the tags, Ali, et al., 2010;
Mahmood, et al., 2013. A wide scale of applications is well studied in the literatures , Nambiar,
2009; Idris, et al., 2009; and Lien, et al., 2012. These applications involve, but are not limited
to, supply chain, production and manufacturing, healthcare and medicine, construction,
hospitality, parking management, transportation, attendance, tracing, and tracking. Thus, RFID
becomes cost effective because the price of individual tags is reduced with the increase in
manufactured volumes. Other opportunities will arise as the technology develops. Building on
earlier works, this paper proposes the use of RFID in developing a recycling rewarding system
(RRS).
Recycling involves processing the used materials into new products to prevent the wastage of
potentially useful materials, reduce the consumption of fresh raw materials, reduce energy
usage, reduce air pollution (from incineration) and water pollution (from land filling) by
decreasing the need for conventional waste disposal, and lower greenhouse gas emissions
compared with virgin production , Murphy, 1993. Recycling is a key component of modern
waste reduction and is the third component of the ―Reduce, Reuse, and Recycle‖ waste
hierarchy , EPA, 2013.
To understand the environmental effects of recycling, consider the fact that recycling 1 kg of
aluminum saves up to 6 kg of bauxite, 4 kg of chemical products, and 14 kWh of electricity ,
EPA, 2013. In other words, aluminum recycling provides up to 95% savings for both energy ,
Murphy, 1993. and air pollution , EPA, 2013. As another example, cited from Proclamation
7250 on America Recycles Day: ―Buying recycled products conserves resources, reduces water
and air pollution, saves energy, and creates jobs. Producing 1 ton of paper from recycled pulp
saves 17 trees, 3 cubic yards of landfill space, and 7000 gallons of water. It also reduces air
pollutants by 60 pounds, saves 390 gallons of oil, and conserves 4200 kilowatt hours of
energy—enough to heat a home for half a year. Estimates show that 9 jobs are created for every
15,000 tons of solid waste recycled into new products‖ , Clinton, 1999. Thus, the importance
of recycling on green environment is summarized as follows:
 Recycling reduces our reliance on landfills and incinerators.
 Recycling protects our health and environment when harmful substances are removed
from the waste stream.
 Recycling conserves our natural resources because it reduces the need for raw materials.
An economic value creation in a proactive green manufacturing strategy results from an
incremental contribution margin due to the sales of products made from regenerated materials.
This measure identifies whether the take-back and regeneration of end-of-life products can also
be justified from an economic viewpoint aside from the environmental considerations , Azzone,
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and Noci, 1998 A; Azzone, and Noci, 1998 B. A second approach for firms involves cost
savings. Some examples of potential cost savings include reducing energy consumption, waste
reduction, lowering pollution emissions, smaller environmental fines, improving economic
efficiency, and decreasing environmental cleanup costs , Characklis, and Richards, 1999.
Advances in manufacturing technology have enabled most recycled products to compete both
in price and quality, with products made from virgin materials. However, only 12% of
consumers are True Greens (regularly involved in recycling), 68% are Light Greens (sometimes
involved in recycling), and 20% are Never Greens (never involved in recycling). The so-called
True Greens are still a minority, whereas the Light Greens are the majority of consumers. Thus,
there is a need to encourage the majority of consumers to be True Greens , Hanas, 2007. One
way to achieve this objective is through rewards.
Earlier studies on the role of rewards in environmental management indicate a positive effect
on environmental performance , Daily, et al., 2007; Zutshi, and Sohal, 2003; and Chinander,
2001. For instance, supervisor support behaviors advocating rewards motivate employees to
introduce novel environmental initiatives, Ramus, 2002. Massoud et al. advocate the utilization
of the Scanlon Plan as catalyst to green organizations. This institutionalization serves as a
potential mechanism to enhance the environmental performance of a firm. In summary, the
model is based on the following features: 1) collectiveness and cooperation, 2) employee
participation, 3) quantifiable performance and bonus measures, and an equitable reward system.
A firm predetermines with its employees an allocation ratio for gains in productivity or cost
savings. Employee participation plays an ultimate role in gauging the fairness of the ratio, and
as a result, the ratio remains open to adjustments, Massoud, et al., 2008.
Recycling is important for green environment because it has economical benefits and provides
job opportunities. However, the persons involved in the recycling process, especially the item
collectors, need to be encouraged. Thus, a rewards system is required to make them satisfied.
This will improve recycling significantly, Ramus, 2002; Massoud, et al., 2008. Moreover,
both the industries and individuals will reap the economical benefits of such system. Finally
and more importantly, the system intends to achieve a green environment for the Earth.
Motivated by such goal, this paper proposes a collaborative system, that is, an RFID-based
RRS. The remainder of this paper is organized as follows: Section 2 presents the specification
of the RRS; Section 3 gives the architectural design; Section 4 discusses the implementation
issues; and finally, Section 5 gives the conclusion and suggestions for future works.
2. RRS SPECIFICATION
To state the RRS specification, an inspection technique is used, by considering the following
scenario for recycling in the inspection phase.
A collection center (e.g. a university) is responsible for collecting the recycling material, storing
the recycling items, declaring the types of material, determining the points for each material
and the formula to convert the points to benefits, and reporting the amount available in stock
for each type of material. Recyclable materials include different kinds of glass, paper, metal,
plastic, textiles, and electronics. The types of materials, their corresponding points, and the
formula are controlled by the supervisor of the center. The materials to be recycled are brought
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to a collection center by the collectors. Any person who would like to collect points should
register himself/herself in a collection center. After registration, the collector brings the material
and identifies himself/herself to the system. The weighting operator weighs the material and
selects the type of the collected material from a computerized dialog to update the points for the
corresponding collector in the system. The collector can withdraw his/her points from any
branch of the collecting center (e.g. a cafeteria in a university). Finally, the industrial tracker
tracks the amount of the recycled items available in stock in the recycling center and their
corresponding price formula.
The RRS system involves many actors. The role of each actor is illustrated below:

Supervisor Member(s) – The role of the supervisor is to administrate the whole system.
The tasks include the following:
1. Select the materials to be collected.
2. Consult the environment, ICT, and economical experts to derive a suitable
formula for earning and withdrawing points. There are two formulas based on
economics: the first formula is for buying the collected materials from the
collectors, and the second formula is for selling the collected materials to the
industry.
3. Decide on the scalability of the center and the members involved in the system
(i.e., number of branches for the collecting center, number of operators and their
salaries, method for announcement of the available materials, and their price
formula).

Weighing operator – The role of the weighing operator is to obtain the collected
materials from the collector or to give the collected materials to the industry. In both
cases, the weighing operator selects the material to be weighted and the corresponding
(buying or selling) formula.

Cashier – When the collector wants to withdraw points, he/she identifies himself/herself
and then enters the amount of points to be withdrawn. The system calculates the
corresponding cash to be given to the collector. Similarly, when an industry wants to buy
a material from the collection center, the person who represents the industry identifies
the firm, selects the type of the desired materials, and enters the required amount. The
system calculates the corresponding cash to be received from the firm.

Registrar – The role of the registrar is to assign an identity and enter the information (i.e.,
user name, identity, contact address, e-mail, and mobile phone number) for both the
collectors and industries involved in the recycling system.

Collectors – They are the people involved in collecting the recycled materials. The
collectors should register themselves in the collecting center. The collectors are familiar
with the materials and the corresponding formula to earn the points. They can withdraw
their points from the cashier.

Industries – These are the firms involved in buying the collected materials from the
center. The industrial trackers (employees), similar to the collectors, are familiar with
the amount of the materials and their corresponding formula to buy from the center. The
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employees either track the availability of the materials or provide material information
according to the strategy of the center.
3. RRS ARCHITECTURAL DESIGN
To simplify the work of the operators and save time for the individuals, RRS uses an RFID tag
for user identification. This process can significantly improve the automation of identifying the
persons in the system. Clearly, many tags are required, and the tag type should have a short
distance between the tag and the RFID reader, consume less power, and have low cost, Ali, et
al., 2010. For these reasons, the passive tags are chosen for person identification.
The RRS consists of five modules, namely, database, data entry, points collecting and recording,
points rewarding, and a web module. Each module is described as follows.
3.1. Database Module
The database module is used to store, update, and retrieve all the information on the tags of the
industrial firms as well as the collectors and their corresponding points. The database also
includes the type of recycling material, the points awarded for each material, the amount
available for each type, and the formulas for selling/buying items. For scalability purposes, the
database is shared logically with other RRS modules and connected through a reliable network.
3.2. Data Entry Module
The data entry module is the software used to enter data into the database through a graphical
user interface (GUI). The data entry module consists of two sub-modules that are described as
follows:
3.2.1. Registrar data entry module – The registrar uses this module to enter the information
for each industry/collector into database, and activate their corresponding identities in the
system.
3.2.2. Supervisor data entry module – The supervisor uses this module to add/remove
material, update the points for each material, and enter/update the name for the payment
algorithm (e.g., buying and selling).
3.3. Points Collecting and Recording Module
This module consists of a weighing machine, a passive reader, and a PC. The PC is connected
physically to the weighing machine and the passive reader. The PC running the points
collecting and recording application software. In addition, this module is logically connected to
the database. This module works as follows.
When the collector brings a material for recycling, the operator weighs the material using the
weighing machine. Next, the collector presents his/her tag to an antenna attached to the passive
reader. The passive reader detects the tag and sends the detected information to the PC. The
application software asks the operator through the GUI about the type of the material, in
addition, informs the operator the weight of the material. The application then queries the
database and determines the points for the corresponding material. Next, the application
software displays the old and new points of the collector. The operator can select the type of
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material or cancel the detection process. When the operator presses the proceed button in the
GUI, the application software updates the database for both the collector points and the
available recycling weight of the selected material (i.e., the new weight is added to the old
weight). Otherwise, the operator can cancel the transaction. Similarly, the operator can select to
withdraw material when a firm would like to buy a material. The procedure is similar for the
firm except that the updates of available material are subtracted from the total available
material.
3.4. Points Rewarding Module
This module consists of a passive reader and a PC. The PC is physically connected to the
passive reader. The PC running the points rewarding application software is logically connected
to the database. This module is used by the cashier and works as follows.
In the case of the collector, the cashier selects the collector transaction. The collector then
presents his/her tag to an antenna attached to the passive reader. The passive reader detects the
tag and sends the detected information to the PC. The application software sends a query to the
database and then retrieves the total amount of points. The software calculates the
corresponding money of the retrieved points (using the buying formula). The software then
displays the user name, total points, and the corresponding money. The application software
asks the collector to enter the amount of money to be withdrawn. If the collector agrees on the
withdrawn transaction (by clicking proceed), the total number of points and the total money are
updated. The cashier gives the cash to the collector. To terminate the transaction, the operator
can press a cancel button.
Similarly, in the case of a firm, the cashier selects the firm transaction. The employee then
presents his/her tag to an antenna attached to the passive reader. The passive reader detects the
tag and sends the detected information to the PC. The application software sends a query to the
database and then retrieves the total amount of materials and their corresponding points. The
application software asks the employee to select the material(s) and the desired weight through
the GUI. Next, the software calculates the corresponding money of the desired amount of
materials (using the selling formula). The software then displays the firm name, the weight of
materials, the corresponding points, and the amount of money. If the employee agrees on the
transaction (by clicking proceed), the total amount of the selected materials is updated. The
cashier takes the cash from the employee. To terminate the transaction, the cancel button is
pressed.
3.5. Web Module
This module consists of a web server and has a logical connection to the database. The web
module retrieves the information stored in the database and displays the name of materials, the
corresponding points, the total available amounts of the materials, and the formulas for buying
and selling. The web module also displays the desired information for remote users. The user
can be the collector (to check their points or the buying formula) or the industry (to see the
items provided by the collection center and the corresponding amounts and selling formula).
4. RRS IMPLEMENTATION
This section describes the implementation issues for RRS. It should be noted that various
implementations are possible.
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The weighing machine is chosen as a third-party commercial machine. MySQL server is
selected as the database server and Apache Tomcat as the web server. An in-house USMUHF
passive reader serves as the RFID reader, Ali, et al., 2010. The Java programming language is
used for the software application. These components are selected for their cross-platform
functionality, that is, they support different hardware and operating systems.
The weighing machine is connected to the PC using the serial communication port (RS232),
whereas the passive RFID reader is connected to the PC through the LAN. The application
software has a configuration management feature. This feature is useful in setting the serial port
and the TCP/IP port during the first run of the application.
A typical entry to the database for the supervisor is illustrated in Table 1. The first column
presents the materials, the second column presents the green points for each material, and the
third and fourth columns are the buying and selling formulas, respectively. The entry for the
buying/selling formula shows the class name and the corresponding method to be invoked for
the calculations. The algorithm for buying and selling is simple, that is, paying one cent and
two cents, respectively, for each point.
Aside from the monetary benefits, the supervisor offers other incentives for collectors. For
example, any collector with more than 300 points can own a locker for one semester for free.
Moreover, a gift worth 1000 Malaysian Ringgit (RM) will be given to the green student who
can collect the maximum earning points during the semester.
The points collecting and recording GUI starts in the waiting state of the module, that is, no tag
is detected. When the tag is detected for a collector, the GUI shows the identity of the tag, the
earned points, and the weight displayed by the weighing machine in grams (g). Finally, the GUI
enables the operator to select the type of material or even cancel the operation as depicted in
Fig. 1(a). When the operator selects the material, a dialog will appear to verify the information
entered. The weight shown by the weighing machine, the tag identity, the current points, the
points to be given, and the total cumulative points will be shown on the display. The operator
can press the ―Proceed‖ button to confirm the information or press the ―Cancel‖ button to
terminate the operation and return to the waiting state, as shown in Fig. 1b. The updating of the
points is conducted using the following formulas:
New Points = Weight (kg) * Green Point of the material
(1)
Total points=Old points+New points
(2)
For instance, when a collector (already with 78.2 points) brings 440 g of metal tin, the operator
presses the ―Metal tin‖ button, Fig.1a, and then
New points= 440/1000 *15=6.6 points.
Total points=78.2+6.6=84.8 Fig.1b.
In the points awarding software, the card’s number (CN) can be entered in two ways: manually
or through the RFID tag-detection system (depends whether the passive reader is available at
the payment branch or not). After identifying the tag for a collector, the payment system
enables the cashier to check, enter the amount of points to be withdrawn by the collector, trace
the record of the collector, and finally proceed or cancel the transaction, as depicted in Fig. 2.
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Similarly, when a firm tag is detected, the dialog appears to the employee and enables him/her
to enter the desired amount for each material. Next, a dialog displays the total amount of points
and the corresponding cash to be paid to the center. For example, consider a firm that wants to
buy 1 ton of aluminum tin can, 500 kg of computer paper, and 100 kg of compact disc. In this
case:
Total Points=330*1000+500*48+55*100
=359,500 points.
Using the USM_Selling formula, the cash amount=RM 7190.00.
5. CONCLUSION
This paper presented a recycling system called RRS that aims to keep the environment green.
The use of low-cost passive tags significantly reduces the cost of modernization and
identification automation. This paper also presented the design and implementation of the
system. An incremental prototype was discussed as a case study. The modular design of the
system makes it scalable, easy to use, and extendable horizontally (by adding more
functionality to the system) and vertically (by supporting various implementations of the
system). For instance, instead of tracking the available material passively from the web site, an
alternative active tracking system can be achieved by sending an e-mail or SMS to the
interested firm or industry. Currently, a pilot testing of the system is undergoing in Universiti
Sains Malaysia (USM). As part of future work, a web-based material tracking and tracing
system is currently being developed to make the industry track and trace materials around
different universities and countries.
6. ACKNOWLEDGEMENTS
The author would like to give his sincere gratitude and thanks to the Vice Chancellor of
the Universiti Sains Malaysia, and the Auto Identification Laboratory (AIDL) research group at
the School of Electrical and Electronics Engineering for granting this research, providing all
the required hardware, and putting the RRS at the University.
7. REFERENCES
Akyildiz, I. F., Su, W., Sankarasubramaniam, Y., and Cayirci, E., 2002, A Survey on Sensor
Networks, IEEE Communications Magazine, Vol. 40, No. 8, PP. 102-114.
Ali, M. F. M., Younis, M. I., Zamli, K. Z., and Ismail, W. , 2010, Development of Java Based
RFID Application Programmable Interface for Heterogeneous RFID System. Journal of
Systems and Software, Vol. 83, No. 11, PP. 2322–2331.
Azzone, G. and Noci, G. , 1998 A, Identifying Effective PMSs for the Deployment of Green
Manufacturing Strategies, International Journal of Productions & Operations Management, Vol.
18, No. 4, PP. 308-335.
Azzone, G. and Noci, G. , 1998 B, Seeing Ecology and Green Innovations as a Source of
Change, Journal of Organizational Change Management, Vol. 11, No. 8, PP. 94-111.
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Characklis, G. W., and Richards, D. J., 1999, The Evolution of Industrial Environmental
Performance Metrics: Trends and Challenges, Corporate Environmental Strategy, Vol. 6, No. 4,
PP. 387-398.
Chen, M., Gonzalez, S., Zhang, Q., Li, M., and Leung, V., 2010, A 2G-RFID Based Ehealthcare System, IEEE Wireless Communications Magazine, Vol. 17, No. 1, PP. 37-43.
Chinander, K. R., 2001, Aligning Accountability and Awareness for Environmental
Performance in Operations, Production and Operations Management, Vol. 10, No. 3, PP. 276291.
Clinton, W. J., 1999, America Recycles Day, in Proclamation 7250 of November 15, USA.
Daily, B. F., Bishop, J. W., and Steiner, R., 2007, The Mediating Role of EMS Teamwork as it
Pertains to HR Factors and Perceived Environmental Performance, Journal of Applied
Business Research, Vol. 23, No. 1, PP. 95-110.
EPA, 2013, Recycling, United States Environmental Protection Agency, Annual Report, 2013.
Hanas, J. , 2007, A World Gone Green, Speacial Report: Eco-Marketing, Advertising Age.
Idris, M. Y. I., Tamil, E. M., Razak, Z., Noor, N. M., and Km, L. W., 2009, Smart Parking
System using Image Processing Techniques in Wireless Sensor Network Environment,
Information Technology Journal, Vol. 8, No. 2, PP. 114–127.
Lien Y. H., Hsi, C. T., Leng, X., Chiu, J. H., and Chang, K. C., 2012, An RFID Based Multi-Batch
Supply Chain Systems, Wireless Personal Communications, Vol. 63, No. 2, PP. 393-413.
Mahmood, B. M. R., Younis, M. I., and Ali, H. M., 2013, Construction of a General Purpose
Infrastructure for Rfid-Based Applications, Journal of Engineering, Vol. 19, No. 11, PP. 14251442.
Massoud, J. A., Daily, B. F., and Bishop, J. W., 2008, Reward for Environmental Performance:
Using the Scanlon Plan as Catalyst to Green Organisations, International Journal of
Environment, Workplace and Employment, Vol. 4, No. 4, PP. 15-31.
Murphy, P., 1993, The Garbage Primer: The League of Women Voters, New York: Lyons &
Burford.
Nambiar, A. N. , 2009, RFID Technology: a Review of its Applications, in Proceedings of the
World Congress on Engineering and Computer Science 2009 (WCECS 2009), San Francisco,
USA, PP. 1-7.
Ramus, C. A. , 2002, Encouraging Innovative Environmental Actions: What Companies and
Managers Must Do, Journal of World Business, Vol. 37, No. 1, PP. 151- 164.
Zutshi, A., and Sohal, S., 2003, Stakeholder Involvement in the EMS Adoption Process,
Business Process Management Journal, Vol. 9, No. 2, PP. 133-148.
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Table 1. Typical data entry for supervisors in the USM recycling center.
Green
Buying
Selling
Points/kg
Formula
Formula
All types of paper
25
USM_Buy
USM_Sell
Computer paper
48
USM_Buy
USM_Sell
Mineral water bottles
50
USM_Buy
USM_Sell
Aluminum tin can
330
USM_Buy
USM_Sell
Glass bottles
2
USM_Buy
USM_Sell
Metal tin (milk tin, biscuit tin)
15
USM_Buy
USM_Sell
Mixed-plastics (PVC, water containers)
30
USM_Buy
USM_Sell
55
USM_Buy
USM_Sell
20
USM_Buy
USM_Sell
MATERIALS
Compact Disc (CD-ROM, Audio CD,
VCD, DVD)
Mixed-metals
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(a) Tag detection and type selection process for an authorized tag.
(b) Confirmation dialogue
Figure 1. Snapshots of the points collecting and recording.
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Figure 2. Snapshot of the points awarding system.
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Experimental Studies and Finite Element Modeling of Piles and Pile Groups
in Dry Sand under Harmonic Excitation
Saad Faik Abbas Al-Wakel
Lecturer
University of Technology-Baghdad
[email protected]
Mahmoud Rasheed Mahmoud
Assistant professor
University of TechnologyBaghdad
Ahmed Sameer Abdulrasool
Lecturer
University of TechnologyBaghdad
ABSTRUCT
Foundations
supporting reciprocating engines, radar towers, turbines, large electric
motors, and generators, etc. are subject to vibrations caused by unbalanced machine forces as
well as the static weight of the machine. If these vibrations are excessive, they may damage the
machine or cause it not to function properly. In the case of block foundation, if changes in size
and mass of the foundation do not lead to a satisfactory design, a pile foundation may be used.
In this study, the dynamic response of piles and pile Groups in dry sand is investigated
experimentally. The analysis involves the displacement response under harmonic excitation. In
addition, a numerical modeling by using finite element method with a three-dimensional
formulation is adopted to simulate the experimental model. The results of the numerical model
showed that a good agreement is achieved between the predicted dynamic response and that
measured from the experimental model.
Key words: dynamic analysis, finite element method, pile foundations.
‫دراساث عمليت ونمذجت العنصز المحذود للزكائز ومجموعاث الزكيزة في الزمل الجاف ححج حأثيز األسخثارة‬
‫المخناسقت‬
‫أحمذ سميز عبذ الزسول‬
‫مدزض‬
‫ بغداد‬- ‫اندامعت انخكىُنُخٕت‬
‫محمود رشيذ محمود‬
‫أظخاذ معاعد‬
‫ بغداد‬- ‫اندامعت انخكىُنُخٕت‬
‫سعذ فايق عباس‬
‫مدزض‬
‫ بغداد‬- ‫اندامعت انخكىُنُخٕت‬
‫الخالصت‬
‫ انخ حكُن خاضعت‬،‫ َمُنّداث‬،‫ محسّكاث كٍسبائٕت كبٕسة‬،‫ حُزبٕىاث‬،‫زاداز‬
‫ أبساج‬،‫األظط انخٓ حعىد انمحسكاث انخسددٔت‬
ِ
‫ قَ ْد‬،‫ث مفسطت‬
ِ ‫ إذا كاوج ٌري اإلٌخصاشا‬.‫ث انخٓ حعببٍا قُِ انماكى ِت غٕس انمخُاشو ِت باإلضافت إنّ انُش ِن انعاك ِه نهماكى ِت‬
ِ ‫نإلٌخصاشا‬
َ
َ
‫األظاض ال‬
‫ت‬
‫َكخه‬
‫حدم‬
ٓ‫ف‬
‫انخغٕٕس‬
‫كان‬
‫إذا‬
،
‫انكخهت‬
‫ذاث‬
‫األظط‬
‫حانت‬
ٓ‫ف‬
.‫صحٕح‬
‫بشكم‬
‫م‬
‫حشخغ‬
‫ال‬
‫قد‬
َ
‫أ‬
‫ت‬
‫هماكى‬
‫ن‬
‫ضسز‬
‫حعبب‬
َ
ِ
ِ
ِ
ُ
ْ ‫ فأن أظط انسكائص ٔمكه‬, ‫ٔان إنّ حصمٕم مقىع‬
‫ األظخدابت اندٔىامٕكٕت نهسكٕصة َنمدمُعت زكائص‬،‫فٓ ٌري اندزاظ ِت‬.‫أن حعخَعم ُم‬
ِ ‫ُٔؤ ّد‬
‫ انىمرخت‬,‫ باإلضافت انّ ذنك‬.‫ َٔخض ّمهُ انخحهٕ ُم َز َّد اإلشاحتَ ححج األظخثازة انمخىاظقت‬.ٓ‫انداف ُٔخح ّسِ عىٍا بشكم عمه‬
‫م‬
‫انسم‬
ٓ‫ف‬
ِ
ِ
ْ‫انعدد‬
‫انىمُذج‬
‫ حبٕه وَخائِ َح‬.ٓ‫انىمُذج انعمه‬
‫انعىصس انمحدَد ِة َمع صٕاغت ثالثٕت األبعاد حم حبىٍٕا نخمثٕم‬
‫انعددٔت بئظخعمال طسٔق ِت‬
ِ
ِ
ِ
ِ
ّ
ْ
ّ
َ
ِّ
.ٓ‫انىمُذج انعمه‬
‫ه‬
‫م‬
ً‫قٕاظ‬
‫حم‬
ْ‫انر‬
‫َذنك‬
‫ع‬
‫ق‬
ُ
‫خ‬
‫م‬
‫ان‬
ٓ‫اندٔىامٕك‬
‫د‬
‫س‬
‫ان‬
‫بٕه‬
‫انىخائح‬
ٓ‫ف‬
ً‫ححقٕق‬
‫بأن ٌىانك حُافق خٕد حم‬
َ
ِ
ُ
ِ
ِ
ِ َ
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1. INTRODUCTION
In the recent years, there is a dramatic progress in the develop-merit of theories for dynamic
analysis of piles. The rapid development of pile analysis is prompted by the growing use of pile
foundations in traditional areas. As well as it’s used as a deep foundation for building, it’s used
also as a machine foundations and their large scale application used in new application of civil
engineering such as nuclear power plants and offshore towers. Many methods have been used to
examine the foundation behavior under dynamic loadings; they are basically classified as
experimental and theoretical approaches. The experimental approach includes models and field
studies on existing foundations while the theoretical approach includes analytical and numerical
solutions.
There are various types of dynamic tests of piles are conducted, they differ primarily according
to the size of piles, test medium, technique employed, and aim as following , Novak, 1987.
(1) Full scale field tests
In these tests full scale piles are installed in natural deposit. Sometimes the piles are
instrumented with strain gauges to monitor strains and thus axial forces or bending moments.
Often the piles are loaded by a rigid concrete or steel test body. The purpose of this loading is to
lower the pile resonant frequencies and to bring them within the frequency range of the exciter, if
an exciter is used, and to lower the damping ratio which facilitates the analysis of the
experimental data.
(2) Small prototype field tests
Field experiments with small prototype piles are less demanding than full scale experiments in
terms of equipment, cost and effort, and make it easier to control the conditions of experiments
while still allowing for unobstructed propagation of elastic waves.
(3) Small scale laboratory tests
Small scale laboratory tests are conducted with very small model piles in test bins or tanks. The
small scale laboratory tests are popular because they are inexpensive, easy to organize, and
independent of the weather. Their deficiencies are their inability to work with an undisturbed
natural deposit (which limits the experiments to artificially prepared deposits of sand or
remolded clay), the difficulty in achieving meaningful confining pressure on which soil stiffness
depends and, finally, the limited size of the test box.
2. THE DYNAMIC RESPONSE OF PILE FOUNDATIONS
Das , 1983. presented a method to determine the natural frequency of vertical vibration of the
pile using elastic waves in a bar method. The benefit derived from the use of piles depends on
several factors such as the type of piles to be used, the length of piles, and the portion of load
carried by each pile. The problem was treated as a vertical rod fixed at the base (i.e., at the rock
layer) and free on top.
Novak , 1987. Studied the dynamic behavior of pile and pile groups experimentally. Three types
of test are conducted: steady-state vibration tests using a mechanical oscillator, free vibration
(plucking) tests, and static deflection tests. The excitation forces are produced by means of a
Lazan mechanical oscillator. A typical set of vertical response curves measured with different
intensities of harmonic excitation is considered. The experimental response curves are compared
with theoretical predictions. The first observation made is that the vertical stiffness of the pile
strongly depends on the tip condition unless the pile is quite long or the soil very stiff. Assuming
an end bearing pile, where the floating tip condition is more proper, may result in a very
substantial overestimation of stiffness and a significant underestimation of damping. A proper
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relaxation of the tip, depending on the stiffness of the stratum underlying the tip, is necessary.
This observation is in good agreement with theoretical results.
El-Marsafawi et al. 1992. conducted a field experiments on group of piles supporting rigid
foundations and subjected to harmonic loading. The objective is to investigate the ability of
linear elastic theories of pile-group modeling to predict the response curve characteristics
including the resonant frequency and amplitude. Harmonic vibration tests are conducted on the
pile group in vertical and horizontal directions. In addition, a single pile is tested under harmonic
loading in the vertical direction and in free vibration in the horizontal direction. The theoretical
results are also verified using the more rigorous direct analysis approach. The comparison with
the experiments shown that, the linear theory gives a good estimate of the group stiffness but
overestimates damping of the group.
Boominathan and Lakshmi , 2000. studied the influence of pile-soil interaction on dynamic
characteristics of pile groups. The vertical vibration tests are conducted in a carefully designed
small scale pile test facilities at the laboratory. The analysis of the test results indicate that the
group stiffness increases with increase of frequency up to limiting frequency and then decreases.
The damping constants are substantially high at the low frequencies and decreases with the
increase of the frequency. In addition, it is found that the stiffness is increasing and the damping
is decreasing as the spacing between the piles decreases.
3. PROPERTIS OF MATERIALS USED IN THE EXPERIMENTAL MODEL
The materials used in this study are divided into two parts they are; dry sand and reinforced
concrete for the pile foundation. The standard tests are performed to determine the physical
properties of the sand as follows:
(1) Relative density: The test is carried out according to the (ASTM-D4253 and D4254)
specification.
(2) Specific gravity: The standard test for the specific gravity of the soil particles is performed
according to (ASTM-D854) specification using water the pycnometer method. The physical
properties of the soil are shown in Table 1.
(3) Grain size analysis: The test is carried out according to the (ASTM-D422) specification; the
grain size distribution of the soil is shown in Fig. 1.
(4) Direct shear test: The direct shear test is used to obtain the stress-strain relationship. In
addition, the angle of internal friction ( ) of the sand with a unit weight of 15.0 kN/m3 is
obtained from the same test.. The mechanical properties of the soil obtained from the test are
shown in Table 2.
The tests performed to determine the properties of the concrete and the reinforcement is:
(1) Compression test: The standard test of compressive strength according to (ASTM-C39M)
specification is performed for three samples of cylinders.
(2) Tensile test: The Tensile test of the reinforcement is carried out according to the (ASTME8M) specification.
4. PRPARATION OF EXPERIMENTAL MODEL
The experimental tests are conducted on deep foundations under the effect of harmonic vertical
mode of waves with two groups of piles. In addition, a deep foundation consists of single pile is
tested. A steel mold is used to construct the frame of the deep foundation. The mold for the
single pile consists of two parts linked together with screws. The molds of the experimental
model with two and four piles consist of three parts linked together with screws. The
reinforcement of the pile consists of four bars with 3.0 mm in diameter and the length of the bar
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is 545.0 mm. The spacing between the reinforcement of the pile center to center is 8.0 mm. The
yield strength of the reinforcement (fy) is 290 MPa.
A circumferential wire is used as stirrups, and the spacing between stirrups is 136.0 mm center to
center. The cap is reinforced in two directions where the number of bars in each direction is 9
bars. The length of each bar is 206.0 mm with diameter of 2.0 mm. The space between the
reinforcement center to center is 24 mm and the cover of cap reinforcement is 7.5 mm. The yield
strength of the reinforcement (fy) is 175.0 MPa. In addition, the end of each bar is twisted in the
vertical direction with length of 15.0 mm, and the reinforcement of the pile and cap are linked
together with a wire. The molds and the reinforcement of the experimental model are shown in
Plate 1. Four screws are used to link the mechanical oscillator with the cap of the foundation to
act as a one unit where the screws are fixed at the bottom of the cap. A steel base plate is used to
ensure the spacing between the bolts to put a mechanical oscillator at a specific location, and
then the plate is lifted up.
A concrete with mix of (1:1.5:3) is used to construct the model of the pile foundation, the gravel
is passing through a sieve No.6 (3.35 mm). Chowdhary and Dasgupta , 2009. Recommended
that the water-cement ratio shall be not exceeding 0.45 for a machine foundation. In this work,
the water-cement ratio (w/c) was 0.4. An additive of Structuro 520 (Suporplasticisers) is added
to the concrete mix with a ratio of 1 liter/m3. This additive allows producing a concrete with a
high performance and workability. The concrete of the pile and cap is board continuously and
integrally, and then the mold is placed on a vibration table for 45 second to ensure that no voids
in the concrete and to have a smooth surface of concrete. After 24 hours, the concrete of the pile
foundation is cured for a 28 days.
5. SET-UP OF THE EXPERIMENTAL MODEL
The group interaction factor which has been observed to have a significant effect on the dynamic
response on the system especially for the pile spacing between 2.5D to 3D where D is the overall
diameter of the pile. To ignore the effect of group interaction factor, the distance between the
piles center to center is at least more than 5D , Chowdhary and Dasgupta, 2009. In this study,
the distance between the piles center to center was 6D.
The model of the deep foundations consists of pile with a square cross-section of width 25.0 mm
and length of 550.0 mm. The cap of the piles is made of a reinforced concrete of thickness 30.0
mm. The base of the cap is rising 50.0 mm above the soil surface to avoid the effect of pile raft
condition. The layout of the deep foundation is shown in Fig. 2. A container of steel plate with
dimensions of (600×600) mm and 700 mm height is used, so that the distance from the edges of
the cap and tip of the piles to the boundary of the container is more than 5D of the pile which is
satisfying a non-reflection wave. This behavior can be examined by the numerical model when
the displacement response for this type of foundation returns to zero (i.e., no reflection of the
wave at the boundary).
To prepare the soil of the experimental model, a sandy soil passing through sieve No.18 (1.0
mm) and retained on sieve No.100 (0.150 mm) is used. In the first stage, a soil of 130.0 mm
thickness is placed in the steel container to prepare the bed of soil. Then, the pile foundation is
placed in the container so that the base of the cap is resting on a steel plate with fixed ends as
shown in Plate (2). After that, the container is filled with sand by five layers with thickness of
100 mm for each layer. The density of the soil used 15.0 kN/m3 is specified previously. The
required amount of the soil is weight, and then put in the container. The general procedure of
ASTM-D4253 is adopted to obtain the dry unit weight of the soil. A surcharge load of 37.32
kg/m2 is added on the surface of the soil to avoid vertical movement of surface particles. An
external source of vibration with frequency of 3600 cycles/min is applied up to the soil is
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Journal of Engineering
occupying a specific volume (cross-section area of the container with height of the layer) to give
the required density of the soil. The time required to apply the vibration was found in the
laboratory experimentally and depends on the thickness of layer which is 37 seconds for the bed
layer and 30 seconds for each other layers. The steel plate which supports the foundation is
removed during the test.
To create a small scale model of a dynamic system, a mechanical oscillator consists of an
electrical motor having a maximum rated speed of 6500 rpm through a shift is used to introduce
a harmonic vertical mode of sinusoidal wave. The mechanical oscillator consists of a rotating
disc manufactured from steel with diameter 70.0 mm and thickness 5.0 mm. A single mass (me)
is placed on the rotating disc at an eccentricity, e of (25.0) mm from the axis of rotation. This
arrangement rotates in one direction when it is driven by a motor having a maximum rated speed
of (6500) rpm through a shift, where such an arrangement induces a dynamic force at the base of
the oscillator.
The speed of the motor and hence the mechanical oscillator can be varied which, in turn, causes
a change in frequency of vibration. In addition, a mechanical assemblage is fixed on the disc of
the mechanical oscillator and connected to a tachometer to measure the frequency of the
dynamic system. The dynamic force induced is a frequency dependent for a given mass on the
rotating disc. By varying the mass by means of an external control, it is possible to change the
amplitude of dynamic force for a specific frequency. The amplitude of vertical dynamic force
produced as in Eq. (1):
Fo = me e ω2
(1)
where ω = circular frequency of the dynamic system,
The displacement response of the foundation can be measured by a vibration meter which
converts the electrical signal to a displacement. The main objective of the apparatus is to apply a
harmonic vertical mode of vibration on a pile foundation to determine the displacement
response. The frequency of the dynamic force is controlled by a speed control unit which is
connected to the mechanical oscillator. The displacement of the foundation is measured by the
vibration meter. For all tests, the displacement response is measured at the edge and center of the
cap. The amplitude of the applied dynamic force is ± 99.41 and ± 155.34 N and the circular
frequency (ω) is 209.4 and 261.7 rad/sec, respectively. The displacement of the foundation is
recorded when the steady state is occurred.
The results of the experimental model which are represent the frequency versus displacement of
the pile foundation at the edge and center for different values of amplitude of dynamic force are
shown in Tables 3 and 4. From results of the experimental model, it can be stated that the
maximum amplitude of displacement of the deep foundations occurs at the center of the
foundation. In addition, as the number of piles increases this will lead to a decrease in the
displacement response of the pile foundation due to increase the mass of foundation.
6. THE NUMERICAL SIMULATION OF THE EXPERIMENTAL MODEL BY USING
FINITE ELEMENT METHOD
The Finite element method is one of the most popular numerical methods used for obtaining an
approximate solution for complex problems in various fields of engineering. In this study, a
numerical modeling in prototype scale using a three-dimensional condition is adopted to
simulate the physical model. In addition, the numerical simulation is performed by using the
finite element method with Tcl command language which is implemented in OpenSees program.
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Journal of Engineering
The basic equations of the displacement field in three dimension for the elastic analysis of the
finite element method can be written as in Eq. (2), Zienkiewicz and Taylor, 2005:
∑
(2 a)
∑
(2 b)
∑
(2 c)
where:
= the shape function at a given node, ui,
and
are the nodal displacement.
In matrix form Eq. (3):
{ }=[ ]{ }
(3)
The strain vector can be derived as in Eq. (4)
{ }
[ ]{ }
(4)
where [B] = nodal strain-displacement matrix.
Then stiffness matrix [K] can be as in Eq. (5)
∫ [ ]
[ ]
(5)
where D = elastic coefficient matrix.
The general equation of motion as in Eq. (6)
[ ]{ ̈ }
[ ]{ ̇ }
[ ]{ }={F}
(6)
where [ ] = the mass matrix, [C] = the damping matrix, [K] = the stiffness matrix, { ̈ }
{ ̇ } = nodal velocity vector, {u} = nodal displacement vector, and
{F} = applied load vector.
The considerations of similitude lead to model scale listed in Table 5, the linear dimensions are
scaled 1 to it and the stresses are represented 1 to 1 , Novak, 1987. In this study, the scale factor
(n) was 10. For the full scale model, the dimensions of the pile cap are (2.25× 2.25) m with
thickness of 0.3 m. The length of pile is 5.5 m with a cross-section of (0.25× 0.25) m. A brick
element of 8-node linear isoparametric is used for the finite element discretization. Each node of
element has three degrees of freedom for displacements. To achieve a three-dimensional
analysis, the boundary conditions are applied so that the bottom of the soil is fixed in
displacement while the top surface of the soil is set to be free. To model the steel container, the
constraint on displacement in X and Z directions is applied on nodes at the boundary in Y-Z and
X-Y planes, respectively and the finite element mesh is shown in Fig.3.
The response of pile foundations is greatly affected by the behavior of soil, in which piles are
embedded. Considerable research has been conducted for the analysis of pile groups, in most of
the literature the behavior of the soil is assumed elastic , Maheshwari and Watanabe, 2005.The
poisson's ratio of the fine-grained sand used in the numerical model is 0.25 , Kaniraj, 2008.
According to the laboratory experiments the modulus of elasticity of the soil as shown in
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Table 2.
The material properties of the concrete of foundation, as shown in Table 6, are calculated
according to the ACI code (ACI-318-83), where the compression strength of the concrete, fc is
44.24 MPa. The unit weight of the reinforced concrete is 24.0 kN/m3.
The dynamic load is applied at the surface of the foundation for a specific node at the edge and
center of the cap. The foundation is subjected to a steady state load of sinusoidal function of the
form F = Fo sin (ωt) with amplitude of force 9.941 and 15.534 kN and circular frequency of
20.94 and 26.17 rad/sec, respectively. To cure the artificial oscillation, the numerical damping is
introduced into the analysis which is achieved by using γ = 0.6 and β = 0.3025 in the Newmark
algorithm, Jeremic, 2006. The time step (Δt) of the dynamic analysis for circular frequency
20.94 and 26.17 rad/sec are 0.19882 and 0.31068 second, respectively with a total of 50 steps are
performed.
The displacement responses of the deep foundation with a group of four piles obtained from the
numerical model are shown in Figs. 4 to 7 From these figures, it can be seen that the
displacement reaches maximum amplitude and then rumbling is occurred after that it is return to
zero. This behavior can be attributing to the decay of the wave with time, i.e., the reflection of
the wave at the boundary is not occurred. The comparison between the displacement response of
the foundation with group of four piles which is obtained from the experimental and the
numerical model is shown in Tables 7 and 8 By comparing these results it can be seen that, a
good agreement is achieved.
7. CONCLUSIONS
(1) From the experimental model it can be stated that the maximum amplitude of displacement
of pile foundations occurred at the center. In addition, for a specific frequency, the
amplitude of displacement of the foundation increased with increasing the amplitude of
dynamic force.
(2) The displacement response of the pile foundation under effect of dynamic force, decreases
with the increasing in number of piles due to the increase in the mass of foundation
(3) The numerical modeling using the finite element method can be used to analyze pile
foundations under effect of harmonic excitation.
8. REFFERENCES
- Boominathan, A, and Lakshmi, T. 2000, Dynamic Characteristics of Pile Groups under
Vertical Vibrations, Conference, 12WCEE, Australia.
- Chowdhury, I. and Dasgupta, S. 2009, Dynamics of Structure and Foundation – A Unified
Approach, CRC Press-Balkema, London.
- Das, B. M. 1983, Fundamentals of Soil Dynamics, ELSEVIER- New York, Amsterdam,
Oxford.
- El-Marsafawi, H., Han, Y.C. and Novak, M. 1992, Dynamic Experiments on Two Pile Groups,
Journal of Geotechnical Engineering, ASCE, 118, 4, pp.576-592.
- Jeremic, B. 2006, Computational Geomechanics Inelastic Finite Elements for Pressure
Sensitive Materials,” Lecture, University of California, Davis.
- Kaniraj, S. R 2008, Design Aids in Soil Mechanics and Foundation Engineering, McGraw.
- Maheshwari, B.K and Watanabe, H. 2005, Dynamic Analysis of Pile Foundations Effects of
Material Nonlinearity of Soil,” Electronic Journal of Geotechnical Engineering, EJGE.
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- Novak, M. ,1987, Experimental Studies of the Dynamic Behavior of Piles and Pile Groups,
Dynamic Behavior of Foundations and Buried Structures, Elsevier Applied Science Publishers
(London), pp. 270.
- Zienkiewicz, O.C. and Taylor, R.L. , 2005, The Finite Element Method, McGraw-Hill, London,
UK.
Table 1. Physical properties of the sand.
Parameters
Value
Units
Max dry unit weight, γdry max
16.7
kN/m3
Min dry unit weight, γdry min
36.5
kN/m3
Relative density (%)
32.5
_
Specific gravity, Gs
2.661
_
Table 2. Mechanical properties of the sand.
Parameters
Value
Units
Modulus of elasticity, Es
40424
kN/m2
Angle of internal friction
34o
_
Table 3. Displacement of the pile foundation at the edge obtained from
the experimental model .
Type of
Model
Frequency
(rad/sec)
Amplitude of
Dynamic Force
(N)
Amplitude of Displacement
(mm)
Single Pile
261.7
155.34
0.635
424.6
44.63
0.471
261.7
155.34
0.581
424.6
44.63
0.048
261.7
155.34
0.053
Group of
Two Piles
Group of
Four Piles
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Table 4. Displacement of the pile foundation at the center obtained from
the experimental model .
Type of
Amplitude of
Amplitude of Displacement
Dynamic Force
Edge (mm)
Model
Frequency
(rad/sec)
Single Pile
261.7
155.34
0.810
424.6
44.63
0.502
261.7
155.34
0.710
424.6
44.63
0.051
261.7
155.34
0.057
(N)
Group of
Two Piles
Group of
Four Piles
Table 5. Scales for centrifugal modeling (after Novak, 1987).
Quantity
Full scale
Centrifugal model
Linear dimension
1
1/n
Time ( in dynamic terms )
1
1/n
Force
1
1 / n2
Stress
1
1
Strain
1
1
Density
1
1
Frequency
1
n
Table 6. Material properties of the concrete.
Parameters
Value
Units
Poisson’s ratio, υ
0.20
_
Modulus of elasticity, E
31261184
kN/m2
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Table 7. The displacement response of the pile foundation at the edge.
Frequency
(rad/sec)
Scaled
Frequency
(rad/sec)
Experimental
Numerical
Amplitude of
amplitude of
Dynamic
Dynamic
Force (kN)
Force (kN)
Measured
Predicted
Displacement
Displacement
(mm)
(mm)
424.6
42.46
2.24463
4.463
0.0485
0.0543
261.7
26.17
0.15534
15.534
0.0535
0.0609
Table 8. The displacement response of the pile foundation at the center.
Frequency
(rad/sec)
Scaled
Frequency
(rad/sec)
Experimental
Numerical
Amplitude of
Amplitude of
Dynamic
Dynamic
Force (kN)
Force (kN)
Measured
Predicted
Displacement
Displacement
(mm)
(mm)
424.6
42.46
2.24463
9.941
0.051
0.0547
261.7
26.17
0.15534
15.534
0.057
0.0628
Plate 1. The molds and reinforcement of the experimental model .
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Plate 2. The pile foundation with the steel plate under the cap .
Passing %
100
90
80
70
60
50
40
30
20
10
0
0.01
0.1
1
10
Particle size in mm
Figure 1. Particle-size distribution curve from the grain size analysis test of sand.
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Exciter
Exciter
50
25
25 25
100
25
125
055
25 25
25 25
125
25 25
125
25 25
225
225
25 25
25
055
25
055
25
100
30
50
30
30
Exciter
2014
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Number 7
Figure 2. The layout of the deep foundation (All dimensions in mm).
Load
B
A
A
A
6.3 m
Y
Z
6.0 m
X
6.0 m
Number of elements = 1798 element
Number of nodes = 2408 node
Figure 3. Three-dimensional finite element model.
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0.08
Max Amplitude = 0.054 mm
Displacement (mm)
0.06
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
Time (sec)
Figure 4. Displacement of foundation with group of four piles at the edge
(Point A) of the numerical model (scaled frequency = 20.94 rad/sec).
0.08
Max Amplitude = 0.055 mm
Displacement (mm)
0.06
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
Time (sec)
Figure 5. Displacement of foundation with group of four piles at the center
(Point B) of the numerical model (scaled frequency = 20.94 rad/sec).
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Journal of Engineering
Max Amplitude = 0.061 mm
Displacement (mm)
0.06
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
Time (sec)
Figure 6. Displacement of foundation with group of four piles at the edge
(Point A) of the numerical model (scaled frequency = 26.17 rad/sec).
0.08
Max Amplitude = 0.063 mm
Displacement (mm)
0.06
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
Time (sec)
Figure 7. Displacement of foundation with group of four piles at the center
(Point B) of the numerical model (scaled frequency = 26.17 rad/sec).
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An Experimental Analysis of Embankment on Stone Columns
Dr. Mohammed Y.Fattah
Professor
Building and Construction Department
University of Technology
E-mail:[email protected]
Dr. Bushra S.Zabar
Assistant Professor
College of Engineering
University of Baghdad
E-mail [email protected]
Hanan A. Hassan
Instructor
College of Engineering
University of Al-Mustansiriya
E-mail: [email protected]
ABSTRACT
When embankment is constructed on very soft soil, special construction methods are
adopted. One of the techniques is a piled embankment. Piled (stone columns) embankments provide
an economic and effective solution to the problem of constructing embankments over soft soils. This
method can reduce settlements, construction time and cost. Stone columns provide an effective
improvement method for soft soils under light structures such as rail or road embankments. The
present work investigates the behavior of the embankment models resting on soft soil reinforced
with stone columns. Model tests were performed with different spacing distances between stone
columns and two lengths to diameter ratios of the stone columns, in addition to different
embankment heights. A total number of 21 model tests were carried out on a soil with undrianed
shear strength ≈ 10 kPa. The models consist of stone columns embankment at spacing to diameter
ratio equal to 2.5, 3 and 4. Three embankment heights; 200 mm, 250 mm and 300 mm were
conducted. Three earth pressure cells were used to measure directly the vertical effective stress on
column at the top of the middle stone column under the center line of embankment and on the edge
stone column for all models while the third cell was placed at the base of embankment between two
columns to measure the vertical effective stress in reinforced soft soil directly. The embankment
models constructed on soft clay treated with ordinary stone columns at spacing ratio equal 2.5
revealed maximum bearing improvement ratio equals (1.21, 1.44 and 1.7) for 200 mm, 250 mm and
300 embankment heights, respectively and maximum settlement improvement ratio equals (0.78,
0.67 and 0.56) for 200 mm, 250 mm and 300 embankment heights, respectively.
Keywords: stone columns, soft clay, embankment, laboratory models.
‫تحليل عملي لسذة ترابيه مستىذة علي أعمذة حجرية‬
‫ حىان عذوان حسه‬.‫م‬
‫لسى انطشق ٔانُمم‬
‫ت‬ٚ‫ش‬ٛ‫ انجايعت انًسخُص‬/‫ت انُٓذست‬ٛ‫كه‬
‫ بشرى سهيل زبار‬.‫د‬.‫م‬.‫أ‬
‫ت‬َٛ‫لسى انُٓذست انًذ‬
‫ جايعت بغذاد‬/‫ت انُٓذست‬ٛ‫كه‬
‫ محمذ يوسف فتاح‬.‫د‬.‫أ‬
‫لسى انبُاء ٔاالَشاءث‬
‫ت‬ٛ‫انجايعت انخكُٕنٕج‬
‫الخالصة‬
‫ث‬ٛ‫ ح‬.‫ت ححج انسذة‬ٚ‫ احذٖ ْزِ انطشق ْٕ اسخخذاو انشكائز انحجش‬.‫حخاج انٗ طشق خاصت‬ٚ ‫ت سخٕة‬ُٛٛ‫اٌ اَشاء سذة عهٗ حشبت ط‬
,‫مت انٓبٕط ٔٔلج ٔكهفت االَشاء‬ٚ‫ حمهم ْزِ انطش‬.‫ت سخٕة‬ُٛٛ‫ا ا ٔفعاالا نًشاكم اَشاء انسذة فٕق حشبت ط‬ٚ‫مت حلا الخصاد‬ٚ‫حٕفش ْزِ انطش‬
‫ج ْزِ انذساست‬ٚ‫ اجش‬.‫ك‬ٚ‫فت يثم احًال انسذة نسكت لطاس أ انطش‬ٛ‫ٍ فعانت ححج االحًال انخف‬ٛ‫مت ححس‬ٚ‫ت طش‬ٚ‫حعخبش االعًذة انحجش‬
‫هٕباسكال يع اعًذة‬ٛ‫ ك‬10 ≈ ‫ش يبزٔل‬ٛ‫ت سخٕة راث يمأيت لص غ‬ُٛٛ‫م حضًُج حشبت ط‬ٚ‫ يٕد‬42 ‫لث بهغج‬ٚ‫عهٗ يجًٕعت يٕد‬
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‫ش‬ٛٛ‫ يٍ لطش انعًٕد كًا حى حغ‬2.5, 3, 4 ٘ٔ‫ٍ عًٕد ٔاخش حسا‬ٛ‫ت ب‬ٚ‫بٓا بًُظ يشبع انشكم يع يسافاث يشكز‬ٛ‫ت حى حشح‬ٚ‫ت عاد‬ٚ‫حجش‬
‫ت سخٕة يثبخّ بأعًذة‬ُٛٛ‫لث نسذة يسخُذة عهٗ حشبت ط‬ٚ‫ ٔجذ يٍ دساست يٕد‬.‫ يهى‬300ٔ ‫يهى‬250 ,‫يهى‬200 ‫ث بهغ‬ٛ‫اسحفاع انسذة ح‬
,1.21 ( ‫ث بهغج‬ٛ‫ت ححًم انخشبت ح‬ٛ‫ لابه‬ٙ‫) أظٓشث أعهٗ َسبت ححسٍ ف‬2.5( ‫ت‬ٚ‫ت انًشحبّ بًسافت يشكز‬ٚ‫ إٌ االعًذة انحجش‬، ‫ت‬ٚ‫حجش‬
‫) نسذة‬0.56 ٔ 0.67 ,0.78 ( ‫ َسبت انٓبٕط ٔبهغج‬ٙ‫ ٔألم َسبت ححسٍ ف‬.‫ يهى‬300ٔ ‫يهى‬250 ,‫يهى‬200 ‫) نسذة باسحفاع‬1.7ٔ1.44
.‫ يهى‬300ٔ ‫يهى‬250 ,‫يهى‬200 ‫باسحفاع‬
1. INTRODUCTION
The stone column method is the most effective soft soil improvement with undrained shear
strength cu > 15 kN/m2. Stone columns have higher drainage ability and stiffness than sand drains.
Therefore, ground reinforcement by stone columns solves the problems of the soft soil by providing
advantage of reduced settlement and accelerates consolidation process. Another advantage of this
method is the simplicity of its construction. In extremely soft soil conditions, (cu < 15 kN/m2), lateral
support can be problematic for stone columns , Kempfert, 2003.
Stone columns provide the primary functions of reinforcement and drainage by improving the
strength and deformation properties of the soft soil. Stone columns increase the unit weight of soil
(due to densification of surrounding soil during construction), dissipate quickly the excess pore
pressures generated and act as strong and stiff elements and carry higher shear stresses , Madhav et.
al., 1994, Yoo, 2010. Juran and Guermazi , 1988. performed a series of special modified triaxial
tests on soil reinforced with stone columns to study the effect of area replacement ratio (ar) on the
settlement reduction ratio. The results showed that the increase of replacement ratio from 0.04 to
0.16 results in a significant increase of the resistance of reinforced soil to the applied vertical load
and reduce the settlement reduction ratio. Rao et al. , 1997. conducted a series of tests on stone
columns installed in remolded soft clay with different soil consistencies (IC) to study the effect of
many parameters such as length to diameter of stone column, effect of the placement moisture
content of the surrounding soil, the influence of spacing and the number of columns within the group
on the ultimate bearing capacity. The study showed that the most effective length to diameter ratio
was found to be ranged from 5 to 10. The consistency of soil (Ic = L.L-wn/PI) is one of the main
factors that affect the load carrying capacity of the stone columns and controls the bulb formation.
Al- Shaikhly , 2000. carried out laboratory model tests to investigate the effect of grain size of
backfill material, effect of length of stone columns and effect of area replacement ratio. The optimal
size of backfill material for achieving the maximum value of improvement ranged from (11-14) % of
the column diameter. For all types of the backfill material, the bearing ratio increased with increasing
both the area ratio (ar) and the length to diameter of the columns ratio (L/d).
Al-Qayssi , 2001. conducted model tests to improve the behavior of stone columns by using different
patterns of reinforcement consisting of two and three discs connected to a central shaft. Influence of
spacing between stone columns, effect of footing shape, effect of area replacement ratio and number
of stone columns on ultimate bearing capacity was studied. The circular footing demonstrated a
higher bearing ratio at failure followed by the square then by the rectangular model footings. The
bearing ratio increased with increasing spacing from 2d, 2.5d and 3d c/c for all the three shapes of
model footings. The area replacement ratio showed an insignificant influence on the efficiencies of
the single stone column. Increasing number of stone columns caused a delay in the development of
the bulging shape and hence improves the granular behavior. The bearing ratios for two and three
discs giving an increase of 12% and 40% respectively over the single unreinforced stone columns.
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Al-Waily , 2008. and Fattah et al. 2011. conducted a testing program to study the influence of
stone column number (single, two, three, and four stone columns) , L/d ratio and undrained shear
strength of bed soil on the stress concentration ratio and the bearing improvement ratio (qtreared/
quntreated) of stone columns. The experimental tests showed that the stone columns with L/d=8
provided a stress concentration ratio n of 1.4, 2.4, 2.7, and 3.1 for the soil having a shear strength
cu=6 kPa, treated with single, two, three, and four columns, respectively. The values of n were
decreased to 1.2, 2.2, 2.5, and 2.8 when the L/d=6. The values of n increase when the shear strength
of the treated soil was increased to 9 and 12 kPa. The value of the bearing improvement ratio
decreases with increasing the shear strength of the treated soil.
2. EXPERIMENTAL WORK
2.1 Soil Used
A brown clayey silt soil was brought from a depth of 5 m from the site of a bridge in the sport
city within Al-Basrah government. The soil was subjected to routine laboratory tests to determine its
properties, these tests include: grain size distribution (sieve analysis and hydrometer tests) according
ASTM D422 specifications, Atterberg limits (liquid and plastic limits) according to ASTM D4318
and specific gravity according to ASTM D854 specifications. The results show that the soil consists
of 6% sand, 46% clay and 48% silt as shown in Fig. 1. The soil is classified according to the Unified
Soil Classification System USCS as (CL). Table 1 shows the physical and chemical properties of the
soil used.
2.2 Crushed Stone
The crushed stone, used as a backfill material was obtained from a private mosaic factory. The
size of the crushed stone was chosen in accordance with the guidelines suggested by Al-Shaikhly
2000, where the particle size is about 1/7 to 1/9 of the diameter of stone columns. The particle size
distribution is shown in Fig. 2, the particle sizes range between 2 to14 mm and found to have Ø
value of 41.5º from direct shear test at a dry unit weight of 14.4 kN/m3 corresponding to a relative
density of 55%. The stone is uniform as its uniformity coefficient is less than 4 and considered as
poorly graded. The physical properties are presented in Table 2.
2.3 Sub-base (Embankment Fill Material)
The granular sub-base was brought from Al-Nibaee quarry, north of Baghdad. The sub-base is
commonly used as a fill material for embankment construction. Fig. 3 shows the grain size
distribution of sub-base according to (B.S.1377:1990, Test 7B). The physical and chemical
properties of the sub-base used are shown in Table 3. The sub-base is classified as class (B)
according to the Iraqi SORB ,2003. and as (GW) according to USCS.
3. MODEL DESIGN AND MANUFACTURING
To study the behavior of soft clay reinforced by ordinary stone columns underneath embankment;
an experimental setup with an approximate scale of 1/20 to 1/30 of the prototype was designed and
manufactured to achieve this goal. The setup consists of: steel container, loading frame, hydraulic
system, load cell with load indicator, earth pressure cell, piezometer, strain gauge with strain
indicator, footing model, dial gauges and data acquisition.
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3.1 The Test Setup
Steel container: A movable steel container was constructed to host the bed of soil and all
accessories. The internal dimensions are 1500 mm length, 800 mm width and 1000 mm depth. The
container was made of steel plates 6 mm in thickness braced externally by angles at their corners,
edges and each side. The front side was made from tough glass. The container was provided with
four wheels that allow it to move freely, the container is sufficiently rigid and exhibited no lateral
deformation during preparation of soil and during the test. Plate 1 shows details of the container.
Loading frame and axial loading system: The steel frame consists of two columns and a beam, each
column is fixed at bottom by casting in a concrete slab. The axial pressure is applied through a
hydraulic system which consists of three hydraulic jacks; one in the middle and the others on sides,
used to apply the load on the embankment model, the location of the hydraulic jack is shown in Plate
1. The maximum stress that can be applied on a model footing (250 mm ×500 mm) reaches about
400 kPa. The pressure is measured by a load cell 50 kN in capacity connected to the digital load
indicator as shown in Plate 2.
Earth pressure cell and readout: Earth pressure cells provide a direct means of measuring total
pressure in or on bridge abutments, diaphragm walls, fills and embankments, retaining walls
surfaces, sheet piling, slurry walls and tunnel lining. They may also be used to measure earth bearing
pressure on foundation slabs and footings and at the tips of piles. Plate 3 shows the earth pressure
cell model 4800 manufactured by GEOKON company in U.S.A which is used in this study. Earth
pressure cells are constructed from two thin stainless steel plates welded together around their
periphery and separated by a narrow gap filled with hydraulic fluid. A length of stainless steel tubing
connects the fluid filled cavity to a pressure transducer that converts the fluid pressure into an
electrical signal transmitted by cable to the readout. They can be positioned in the fill at different
orientations so that soil pressure can be measured in two or three directions. The vibrating wire
readout box model GK404 manufactured by GEOKON company in U.S.A, used with earth pressure
cell and piezometer, is portable, low-power, hand-held that is capable of running for more than 20
hours continuously. It is designed for the readout all GEOKON vibrating wire gages and transducers.
Plate 4 shows the readout device. The model GK404 provides 6 excitation positions (A-F) with
display resolution of 0.1 digits. It is displaying the reading of one connector so that a suitable
selector was manufactured to read all the instruments at the same time.
3.2 Preparation of Model Tests
3.2.1 Preparation of soil
Prior to the preparation of the soil bed in the container, the variation of shear strength of the clayey
soil versus time after mixing at different liquidity indices should be obtained. Therefore; six samples
with different liquidity indices were prepared individually; each sample was placed in five layers
inside a CBR mould. Each layer was tamped gently with a special hammer to extract any entrapped
air. The samples were then covered with polythen sheet and left for a period of eight days. Each day,
the undrained shear strength was measured by a portable vane shear device, Plate 5. These tests
provide the time required for the remolded soil to regain strength after a rest period following the
mixing process, Fig. 4. The shear strength of soil decreases with the value of liquidity index and the
influence of time decreases with liquidity index, Fig. 5 shows the variation of shear strength of soil
with liquidity indices after 96 hour curing.
According to the results obtained from Fig. 5, the soil was prepared in the manufactured container
at undrained shear strength cu of 10 kPa and liquidity index of (0.48) corresponding to water content
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of (34.5%). To perform soil preparation, 660 kg of air dried soil was divided into 30 kg groups; each
group was mixed separately with enough quantity of water to get the desired consistency. The
mixing operation was conducted using a large mixer manufactured for this purpose till completing
the whole quantity. After thorough mixing, the wet soil was kept inside tightened polythen bags for a
period of one day to get uniform moisture content. After that, the soil was placed in a steel container
(1500×800×1000) mm in eleven layers; each layer was leveled gently using a wooden tamper of
dimensions (50×100) mm. This process continues for the eleven layers till reaching a thickness of
560 mm of soil in the steel container. After completing the final layer, the top surface was scraped
and leveled to get, as near as possible, a flat surface, then covered with polythen sheet to prevent any
loss of moisture as shown in Plate 6. A wooden board of area similar to that of the soil surface area
(1500× 800) mm was placed on the soil bed. The prepared soil was left for a period of four days to
regain its strength reaching (10 kPa) as was suggested by , Fattah et al. 2011.
3.2.2 Installation of the stone columns
The position of the stone columns to be placed correctly in their proper locations was marked using
a special frame manufactured according to the proposed configuration patterns of stone columns. A
hollow steel pipe with external diameter of 70 mm coated with petroleum jelly was pushed down the
bed to the specific depth (560 mm in fully penetrated stone column with L/d=8 and 350 mm for
partially penetrated stone column with L/d=5) with the aid of the loading system. Plate 7 shows
process of the installation of the stone column. To remove the soil inside the casing, a hand auger,
manufactured for this purpose was used. After that, the casing was removed carefully. The stones
were carefully charged into the hole in ten layers and compacted at relative density of 55% using 50
mm diameter rod to achieve a dry unit weight of 14.4 kN/m3 by a tamping rod. Spacing between
stone columns for each configuration pattern is shown in Plate 8.
3.2.3 Installation of embankment fills
The construction of the embankment fill was started after installation of ordinary stone columns.
A predetermined weight of sub-base was mixed with water by a mixer at optimum moisture content
of 6.3%, this weight of sub-base is sufficient to create a uniform layer 50 mm thick. Each layer was
compacted gently by a wooden tamper of size 75×75 mm to attain a placement maximum dry unit
weight of 21.84 kN/m3 until the desired embankment depth is obtained. Then the top layer was
leveled using a piece of plywood. The final upper width of the embankment is 300 mm. Plate 9
shows the process of preparation of the embankment.
3.2.4 Model testing procedure
The model tests were carried out on natural soil and soil improved with stone columns. The load
cell and load readout used in testing program were calibrated by applying different known static
loads and measuring values through the load cell before using. A footing (250 mm×600 mm) in
dimensions was placed in position on the surface of the embankment model so that the center of the
footing coincides with the center of the load cell and hydraulic jack. Two dial gauges with accuracy
of (0.01 mm/division) were fixed in position to measure the settlements of plate and one dial gauge
was placed in the toe of embankment to measure the soil heave as shown in Plate 10. Loads were
then applied through a hydraulic jack in the form of load increments and measured by the load cell
and recorded by load readout. During each load increment, the readings of the three dial gauges were
recorded. The dial gauge readings were recorded at the end of the period of each load increment.
Each load increment was left for (5 minutes) or till the rate of settlement became constant. Plate 11
presents the tested models after completion of the tests.
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4. PRESENTATION AND DISCUSSION OF TEST RESULTS
The investigation focuses on influence of parameters like, spacing of stone columns, length of
stone column and height of embankment on overall behavior of soft soil treated by stone columns.
The analysis of results of all model tests regarding the applied stress and the corresponding
settlement is illustrated in terms of (q/cu) vs (S/B). The (q/cu) represents the ratio of applied stress to
undrained shear strength of the soft clay, denoted as "bearing ratio" and (S/B) represents the
corresponding vertical settlement as a percent of the model footing width, denoted as "settlement
ratio". To obtain the degree of improvement achieved by each improvement technique, the results are
plotted in the form of (q/cu)t /( q/cu)unt denoted as "bearing improvement ratio", where (q/cu)t is
improved bearing ratio and (q/cu)unt is unimproved bearing ratio.
The improvement in settlement achieved by the model tests is presented in the form of (St/Sunt)
"settlement of treated soil to settlement of untreated soil at the same applied stress" denoted as
"settlement improvement ratio", plotted against the bearing ratio (q/cu).
4.1 Definition of Failure
The failure point is defined when the settlement reaches 36% of the diameter of the stone column
or 10% of the width of the model footing. This definition is compatible with Terzaghi,1947, Hughes
and Withers,1974, Al-Mosawe et al., 1985 , and Fattah et al. 2011.
4.1.1 Model tests on untreated embankment
Three model tests were conducted on beds of untreated soil with undrained shear strengths of 10
kPa at different embankment heights (200 mm, 250 mm and 300 mm). These tests are considered as
reference to obtain the degree of improvement gained after introducing any other type of
improvement technique.
Fig. 6 shows the relationship between the pressure (q) and the surface settlement of embankment
(S) for model test, the figure illustrates that the mode of failure of model test is close to local shear
pattern, due to the rapid rate of deformation. In this test, the footing model is resting on compacted
layer (sub-base) of width relatively ≈ the footing width. The ultimate bearing capacity obtained is 35
kPa, 33 kPa and 30 kPa for the model tests of embankment height 200 mm, 250 mm and 300 mm
respectively based on the failure criterion of (10% of footing width). Fig. 7 shows the bearing ratio
plotted against settlement ratio. The figure demonstrates that the soil bed underneath the 200 mm
embankment height exhibited higher bearing ratio. The bearing ratios at failure (q/cu) for the
embankment- soft soil model are 3.5, 3.3 and 3.0 corresponding to the settlement ratio of 10% of the
footing width and for embankment heights 200, 250 and 300 mm respectively. The results
demonstrate a substantial decrease in bearing ratio with increasing thickness of embankment; this is
due to the increase in the settlement induced by the load from embankment and applied stress.
4.1.2 Model tests of embankment treated with stone columns
Bearing capacity: This series consists of eighteen model tests performed with 200, 250 and 300 mm
embankment overlying soft clay and immediately underneath the model footing. Figs. 8 to 10 show
the relationship between pressure and embankment surface settlement. The results show increase in
the surface settlement with increasing spacing of columns for applied pressure. The maximum
bearing capacity of soil was observed for soft soil improved with stone columns at (s/d =2.5) and the
minimum bearing capacity was for soft soil improved with stone columns at (s/d =4). This may be
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explained by the reduction in area ratio from 12.53 % to 4.89 %. Similar conclusions were obtained
by Han and Gabr ,2002, and Murugesan and Rajagopal ,2006. In addition, it can be noticed that
a higher embankment height resting on stone columns would result in a higher bearing pressure.
Heave at the end of embankment versus horizontal distance from center line of embankment for
different spacing and two L/d ratios are shown in Figs. 11 to 14.
Bearing ratio verses settlement ratio: The variation of bearing ratio (q/cu) versus settlement ratio
(S/B) is shown in Figs. 15 to 17. The results show the effect of ordinary stone columns on bearing
ratio of soil. The spacing ratio (s/d =2.5), demonstrates higher bearing ratio at failure, as compared
with spacing ratio (s/d = 4). Such behavior may be explained due to the confinement effect provided
by the surrounding soil and the adjacent stone columns. As spacing ratio decreased, the confinement
stress provided by the surrounding soil increases. Since the stone columns are stiffer than the
surrounding soil, the stress concentration on the stone columns increases with decreasing the spacing
of stone and embankment height due to soil arching. The values of bearing ratio at failure are
summarized in Table 4. The present results are in agreement with the results obtanied by Juran and
Guermazi ,1988, Craig and Al-Kahafaji ,1997, Rahil ,2007, Al-Waily ,2008 and Fattah et al.
2011.
Bearing improvement ratio verses settlement ratio: To evaluate the amount of improvement
achieved by the ordinary stone column for different spacings over untreated soil, the bearing
improvement ratio (qt/qunt) versus settlement ratio S/B% is presented in Figs. 18 to 20. Peak values
of improvement ratio are observed at nearly S/B about 2% to 4% then drops down and decreased
with increasing settlement ratio. This behavior is attributed to the load transfer mechanism, the stress
is transferred to the stone columns expressing these peak values then it is gradually transferred to the
surrounding soil implied by the drop in the improvement ratio. Also, it can be noticed that the stone
columns with spacing ratio (s/d= 2.5) has higher improvement ratio for different embankment
heights, which is attributed to the increase in area replacement. Table 5 summarizes the values of
bearing improvement ratio at failure.
Settlement improvement ratio versus bearing ratio: Variation of settlement improvement ratio
(St/Sunt) versus bearing ratio (q/cu) for different column spacings and embankment heights is shown
in Figs. 21 to 23.The results imply a decrease in settlement improvement ratio as the bearing ratio
increases until reaching (q/cu) equals 1.48 to 2.8, then a gradual increase in settlement improvement
ratio takes place, the decrease in settlement improvement ratio shows the level of improvement. This
behavior may be attributed to the fact that the decrease in settlement improvement ratio to about
(q/cu) equals 1.48 to 2.8 associated by the increase in bearing ratio and beyond these values, the
excess bulging leads to decrease in load carrying capacity. Also the lower improvement values (high
degree of improvement) are observed when the embankment model is treated by ordinary stone
columns at (s/d = 2.5) compared with the model at (s/d= 4) that revealed a high value of settlement
improvement ratio for different heights of embankment. Settlement improvement ratio at failure is
summarized in Table 6. The results are in agreement with the results of Craig and Al-Kahafaji
1997, Rahil, 2007, Al-Waily, 2008, and Fattah et al. ,2011.
Stress on column versus settlement: The vertical effective stress on column was measured at the top
of the middle stone column under the center line of embankment and on the edge stone column using
earth pressure cell for all models. The stress-settlement behavior of the stone columns for all spacing
ratios is the same as shown in Figs. 24 to 26. The bearing capacity of the stone columns at failure
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corresponding to settlement ratio of 10% increases with decreasing spacing distance between the
columns, as shown in Table 7. These results agree with Hewlett and Randolph, 1988, Low et al.,
1994, Chen et al., 2007, Britton and Naughton, 2008 and Ellis and Aslam, 2009, who measured
the stress using different experimental models for piled embnkment.
The highest vertical effective stress is obtained in case of the least spacing (s/d = 2.5) is used
under the embankment of height 300 mm. This phenomenon is due to the stress concentration
occurring between the adjacent columns as well as due to the confinement effect provided by the
surrounding soil and the adjacent stone columns therefore, the stress concentration on the stone
columns increases with decreasing the spacing of columns. The decrease in vertical effective stress
on the stone column as the spacing increases is due to the yielding of the stone column. Once
yielded, the stiffness of the column decreases, its radial deformability increases due to dilitancy.
Otherwise, the yielding of the column reduces the transfer of vertical load from the soil.
Stress on soft soil versus settlement: The vertical effective stress (σ´vc) in reinforced soft soil was
measured at the base of embankment between two columns using earth pressure cells. The
relationship of the vertical effective stress with surface settlement of embankment is shown in Figs.
27 to 29. The vertical effective stress in the reinforced soft soil increases at a high rate with
increasing spacing between stone columns and decreasing embankment fill height. This may be due
to the excess bulging that occurs in the stone column which leads to decrease in load carrying
capacity. Directly after the embankment construction stages have been finished, the vertical stress in
the reinforced soft soil increases at a very small rate, and as stone columns spacing decreases, the
vertical stress in the reinforced soil decreases and high stress values are generated in the stone
column. This is due to the stress transfer from the soft soil and concentration of the stress in the stone
column (soil arching phenomenon). Table 8 summarizes the values of vertical effective stress on soft
soil at failure corresponding to settlement ratio of 10%. These results agree with Hewlett and
Randolph, 1988, Low et al., 1994, Chen et al., 2008, Britton and Naughton, 2008, and Ellis and
Aslam, 2009, who measured the stress using different experimental models for piled embankment.
5. CONCLUSIONS
The following points are drawn from the test results:
1. The mode of failure for embankment model resting on untreated very soft clay with cu ≈ 10 kPa is
close to local shear failure and the mode gradually changes toward the general shear with using stone
columns.
2. The bearing ratio increases with decreasing spacing distance between the stone columns at any
embankment height. The rate of increasing in bearing ratio of treated models was found to be within
the range (1.08 to 1.2); (1.23 to 1.42) and (1.37 to 1.65) of untreated models for embankment model
height of 200 mm, 250 mm and 300 mm, respectively.
3. The bearing improvement ratio increases with decreasing spacing ratio of stone column for given
embankment. Higher improvement ratio was achieved for the models treated with stone columns at
S=2.5d at any embankment high. The higher values of (qt / qunt) was found to be (1.21, 1.44 and 1.7)
for embankment model of height 200 mm, 250 mm and 300 mm, respectively while lowest
improvement was observed at spacing s = 4d especially for embankment height 200 mm.
4. The improvement in settlement ratio increases as the spacing ratio of stone columns increases. The
lowest value of settlement improvement ratio at failure was observed at s=2.5d for a given
embankment height, which represents higher degree of improvement.
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Hughes, J.M.O. and Withers, N.J. 1974, Reinforcing of Soft Cohesive Soils with Stone Columns,
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Reinforcement, Proceedings of the 5th International Conference on Geotextiles, Geomembranes and
Related Products, Vol. 1, Singapore, pp. 351-356.
Murugesan, S. and Rajagopal, K. 2006, Geosynthetic-Encased Stone Columns: Numerical
Evaluation, Geotextiles and Geomembranes, Vol. 24, No.6, pp. 349–358.
Rahil, F.H. 2007, Improvement of Soft Clay Underneath a Railway Track Model using Stone
Columns Technique, Ph.D. Thesis, Building and Construction Engineering Department, University
of Technology, Iraq.
Rao, S.N., Reddy, K.M. and Kummar, P.H. ,1997, Studies on Group of Stone Columns in Soft Clays.,
Journal of Geotechnical Engineering, Southeast Asian, Vol. 28, No. 2, Dec., pp.165-181.
Yoo C. 2010, Performance of Geosynthetic-Encased Stone Columns in Embankment Construction:
Numerical Investigation, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.
136, No. 8, pp. 1148-1160.
Table 1. Physical and chemical properties of natural soil used.
Property
Value
Liquid limit (LL) %
47
Plastic limit (PL) %
23
Plasticity index (PI) %
24
Specific gravity (Gs)
2.7
% Passing sieve No. 200
94
Sand content % (0.075 to 4.75 mm)
6
Silt content % (0.005 to 0.075 mm)
48
Clay content % (< 0.005 mm)
46
3
Maximum dry unit weight (kN/m ) 18.24
Optimum moisture content (%)
13
Soil symbol according to USCS
CL
Total soluble salts (%)
6.13
SO3 (%)
0.6
Organic matter (%)
1.09
Gypsum content (%)
1.17
pH
8.34
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Table 2: Physical properties of the crushed stone.
Property
Maximum dry unit weight (kN/m3)
Minimum dry unit weight (kN/m3)
Dry unit weight (kN/m3) at
Dr =55%
D10 (mm)
D30 (mm)
D60 (mm)
Coefficient of uniformity (Cu)
Coefficient of curvature (Cc)
Angle of internal friction (Øo)
Specific gravity (Gs)
Value
15.7
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Table 3: Physical and chemical properties of
the sub-base material used.
Property
CBR (%)
Maximum dry unit weight (kN/m3)
Optimum moisture content (%)
D10 (mm)
D30 (mm)
D60 (mm)
Coefficient of uniformity (Cu)
Coefficient of curvature (Cc)
Angle of internal friction (Øo)
SO3 (%)
Total soluble salts (%)
Gypsum content (%)
Organic matter (%)
14.4
3.8
6
7.5
1.97
1.26
41.5
2.65
Figure 1. Grain size distribution of clayey soil used.
72
Value
51
21.84
6.3
0.15
1.5
12
80
1.25
40
0.23
2.93
0.494
0.057
Figure 2. Grain size distribution of
stone used.
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Plate 1. Experimental test container
and loading system.
Figure 3. Grain size distribution
sub-base material used.
Plate 2. Load cell and load readout.
Earth pressure
cells
Plate 3. Earth pressure cell model 4800.
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Plate 4. Readout of pressure cell.
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Plate 5. Portable vane shear device.
Figure 4. Variation of undrained shear strength
with time after mixing.
Figure 5.Variation of the undraied shear
strength with liquidity index.
Plate 6. Soil preparation inside the manufactured
container.
Plate 7. The process of stone column
installation.
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Plate 8. Configuration of patterns of stone
columns, S= 3d.
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Plate 9. Installation of embankment fill.
Plate 10. Model testing procedure.
Plate 11. Stone columns failure (S=3d, L/d=8).
Figure 6. Bearing pressure versus surface
settlement for untreated embankment model.
Figure 7. Bearing ratio versus settlement
ratio for untreated embankment model.
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Figure 8. Bearing pressure versus settlement for embankment model 200 mm high resting on soft
soil treated by stone columns.
Figure 9. Bearing pressure versus settlement for embankment model 250 mm high resting on soft
soil treated by stone columns.
Figure 10: Bearing pressure versus settlement for embankment model 300 mm high resting
on soft soil treated by stone columns.
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Figure 11. Settlement distribution at the base of embankment model 200 mm high constructed on
soft soil treated by stone columns and L/d = 8.
Figures 12. Settlement distribution at the base of embankment model 200 mm high constructed on
soft soil treated by stone columns and L/d = 5.
Figures 13. Settlement distribution at the base of embankment model 300 mm high constructed on
soft soil treated by stone columns and L/d = 8.
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Figures 14. Settlement distribution at the base of embankment model 300 mm high constructed on
soft soil treated by stone columns (OSC) and L/d = 5.
Table 4. Bearing ratio at failure for embankment model constructed on soft clay treated by stone
columns.
Bearing ratio, q/cu
Spacing
H=200 mm H=250 mm H=300 mm
L/d ratio
5
8
5
8
5
8
Untreated
3.5
3.3
3.0
soil
S= 2.5d
4.1
4.2
4.3
4.7 4.6
5.0
S= 3d
3.9
4.0
4.2
4.3 4.3
4.5
S= 4d
3.65 3.8
3.8
4.05 4.0
4.1
Table 5. Bearing improvement ratio at failure for embankment models constructed on soft clay
treated by stone columns.
Bearing improvement ratio, qt /qunt
Spacing
H=200 mm H=250 mm H=300 mm
L/d ratio
S= 2.5d
S= 3d
S= 4d
5
1.2
1.11
1.06
8
1.21
1.15
1.09
5
1.38
1.30
1.20
78
8
1.43
1.36
1.23
5
1.63
1.42
1.35
8
1.7
1.55
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Table 6. Settlement improvement ratio at failure for embankment models constructed on soft clay
treated by stone columns.
Settlement improvement ratio, St/Sunt
Spacing
L/d ratio
S= 2.5d
S= 3d
S= 4d
H=200 mm
5
8
0.88 0.78
0.89 0.81
0.96 0.91
H=250 mm H=300 mm
5
8
5
8
0.72 0.67 0.61 0.56
0.78 0.70 0.70 0.62
0.88 0.72 0.74 0.70
Table 7. Vertical effective stress on stone column at failure for embankment models constructed on
soft clay treated by 7stone columns.
Stress on column (kPa)
Spacing
L/d
H=200 mm
5
8
H=250 mm
5
8
H=300 mm
5
8
S= 2.5d
16
18.8
23.6
31
25
36
S= 3d
15
17
19.8
23.6
22.8
31
S= 4d
11.6
13.3
14.5
19.8
17.5
21
Table 8. Vertical effective stress in soil at failure for embankment models constructed on soft clay
treated by stone columns.
Stress in soil (kPa)
Spacing
L/d
H=200 mm
5
8
H=250 mm
5
8
H=300 mm
5
8
S= 2.5d
23
22.5
19.8
18
18.3
16.2
S= 3d
27.2
26.5
24.8
23.9
22
20.5
S= 4d
30.5
27.5
27
25.8
24.6
23
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Figure 15. Bearing ratio versus settlement ratio for embankment model 200 mm high resting on soft
soil treated by stone columns.
Figure 16. Bearing ratio versus settlement ratio for embankment model 250 mm high resting on
soft soil treated by stone columns.
Figure 17. Bearing ratio versus settlement ratio for embankment model 300 mm high resting on
soft soil treated by stone columns.
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Figure 18. Bearing improvement ratio versus settlement ratio for embankment 200 mm high resting
on soft soil treated by stone columns.
Figure 19. Bearing improvement ratio versus settlement ratio for embankment 250 mm high resting
on soft soil treated by stone columns.
Figure 20.Bearing improvement ratio versus settlement ratio for embankment 300 mm high resting
on soft soil treated by stone columns.
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Figure 21. Settlement improvement ratio versus bearing ratio for embankment 200 mm high resting
on soft soil treated by stone columns.
Figure 22. Settlement improvement ratio versus bearing ratio for embankment 250 mm high resting
on soft soil treated by stone columns.
Figure 23. Settlement improvement ratio versus bearing ratio for embankment 300 mm high resting
on soft soil treated by stone columns.
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Figure 24. Vertical effective stress on column at failure versus surface settlement for embankment
model of 200 mm height constructed on soft soil treated by stone columns.
Figure 25. Vertical effective stress on column at failure versus surface settlement for embankment
model of 250 mm height constructed on soft soil treated by stone columns.
Figure 26. Vertical effective stress on column at failure versus surface settlement for embankment
model of 300 mm height constructed on soft soil treated by stone columns.
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Figure 27. Vertical effective stress in soil at failure versus surface settlement for embankment model
of 200 mm height constructed on soft soil treated by stone columns.
Figure 28. Vertical effective stress in soil at failure versus surface settlement for embankment model
of 250 mm height constructed on soft soil treated by stone columns.
Figure 29. Vertical effective stress in soil at failure versus surface settlement for embankment model
of 300 mm height constructed on soft soil treated by stone columns.
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A Multi-variables Multi -sites Model for Forecasting Hydrological
Data Series
Rafa H. Al-Suhili
Prof. ,Civil Engineering Dept., College of Engineering,
University of Baghdad, Iraq.
A visiting Professor to the City College of New York, New
York, USA.
Email: [email protected]
Nawbahar F. Mustafa
Lecturer, Dams and Water resources Eng., College
of Engineering, University of Sulaimania.
ABSTRACT
A multivariate multisite hydrological data forecasting model was derived and checked
using a case study. The philosophy is to use simultaneously the cross-variable correlations,
cross-site correlations and the time lag correlations. The case study is of two variables, three
sites, the variables are the monthly rainfall and evaporation; the sites are Sulaimania, Dokan, and
Darbandikhan.. The model form is similar to the first order auto regressive model, but in
matrices form. A matrix for the different relative correlations mentioned above and another for
their relative residuals were derived and used as the model parameters. A mathematical filter was
used for both matrices to obtain the elements. The application of this model indicates it's
capability of preserving the statistical characteristics of the observed series. The preservation was
checked by using (t-test) and (F-test) for the monthly means and variances which gives 98.6%
success for means and 81% success for variances. Moreover for the same data two well-known
models were used for the sake of comparison with the developed model. The single-site singlevariable auto regressive first order and the multi-variable single-site models. The results of the
three models were compared using (Akike test) which indicates that the developed model is
more successful ,since it gave minimum (AIC) value for Sulaimania rainfall, Darbandikhan
rainfall, and Darbandikhan evaporation, while Matalas model gave minimum (AIC) value for
Sulaimania evaporation and Dokan rainfall, and Markov AR (1) model gave minimum (AIC)
value for only Dokan evaporation).However, for these last cases the (AIC) given by the
developed model is slightly greater than the minimum corresponding value.
Key words: forecasting, multi-sites, multi-variables, cross sites correlation, serial correlation,
cross variables correlations, hydrology.
‫الخالصة‬
‫ حعخوذ فلسفت‬.‫حن اشخماق ًوْرس حٌبأ بالب٘اًاث الِ٘ذسّلْص٘ت لوخغ٘شاث هخخلفت ّفٖ هْالع هخعذدة ّححم٘مَ باسخخذام حالت دساس٘ت‬
ٔ‫الٌوْرس علٔ االسخخذام االًٖ لوعاهالث االسحباط الوكاً٘ت ّحلك الخٖ حْصذ ب٘ي الوخغ٘شاث فٖ الوْلع الْاحذ باإلضافت ال‬
.‫ دّكاى ّ دسبٌذخاى‬,‫ الوطش ّالخبخش فٖ السل٘واً٘ت‬,‫ الحالت الذساس٘ت ُٖ لوخغ٘شٗي فٖ رالرت هْالع‬.ٌٖ‫االسحباط الخسلسلٖ الزه‬
‫ للٌوْرس هصفْفخٖ هعاهالث االّلٔ راث‬. ‫اى الٌوْرس شبَ٘ بٌوْرس االسحباط الخسلسلٖ ّلكي هعاهالحَ بص٘غت الوصفْفاث‬
‫ بٌ٘ج الٌخائش لذسة الٌوْرس علٔ الخٌبؤ‬.‫عٌاصش حوزل هعاهالث االسحباطاث الٌسب٘ت ّالزاً٘ت حوزل هعاهالث بماٗا االسحباط الٌسب٘ت‬
‫ ّكاًج ًسب الٌضاط‬,‫بالوعلْهاث بصْسة صح٘حت ح٘ذ حن اسخخذام اخخباسٕ فحص الفشق باألّساط الحساب٘ت ّالخباٗي‬
ّ‫ حن بٌاء ًوْرس ر‬,‫ ّلغشض الوماسًت ب٘ي الٌوْرس الوشخك ّالٌوارس الوعشّفت فٖ ادب٘اث الوْضْع‬.ٖ‫( علٔ الخْال‬81,98 (
‫الوخغ٘ش الْاحذ لكل هخغ٘ش هي الوخغ٘شاث الوسخخذهت(سخت ًوارس)ّ رالد ًوارس هي ًْع الٌوارس الوخعذدة الوخغ٘شاث ًوْرس لكل‬
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‫ بٌ٘ج الٌخائش باى‬.‫ حن هماسًت ًخا ئش ُزٍ الٌوارس هع الٌوْرس الوشخك باسخخذام اخخباس (اكاٗكٖ) الزٕ ٗسخخذم لِزا الغشض‬. ‫هْلع‬
‫الٌوْرس اعطٔ الل الم٘ن لالخخباس بالٌسبت للوطش فٖ السل٘واً٘ت ّ دسبٌذخاى ّالخبخش لذّكاى اها ف٘وا ٗخص ًخائش بم٘ت الوخغ٘شاث‬
.‫كاًج ل٘ن االخخباس اعلٔ بمل٘ل عي الم٘ن الصغشٓ الوٌاظشة‬
1. INTRODUCTION
Weather generation models have been used successfully for a wide array of applications. They
became increasingly used in various research topics, including more recently, climate change
studies. They can generate series of climatic data with the same statistical properties as the
observed ones. Furthermore, weather generators are able to produce series for any length of time.
This allows developing various applications linked to extreme events, such as flood analyses,
and draught analysis, and hence putting proper long term water resources management to face
the expected draught or flood events. There exist in the literature many types of stochastic
models that simulate weather data required for various water resources applications in
hydrology, agriculture, ecosystem, climate change studies and long term water resource
management.
Single site models of weather generators are used for forecasting a hydrological variable at a
single site independent of the same variable at the near sites, and thus ignoring the spatial
dependence exhibited by the observed data. On the other hand single variable forecasting models
are used for forecasting a hydrological variable in a site independent of the other related
variables at the same site, thus ignoring the cross variables relations that physically exist between
these variables. Tobler, 1970, mentioned in the first law of geography that “everything is related
to everything else, but near things are more related than distant things.” The most commonly
used multi-sites stochastic weather models are of the form proposed by Richardson, 1981. for
daily precipitation, maximum temperature, minimum temperature, and solar radiation , Wilks,
1999.These models forecast a hydrological variable at multiple sites simultaneously, hence
simulate the cross sites dependency between these sites. The Multi-variables models are similar
to the multi-sites model but simulate the cross variables dependency that exists between some
variables at a certain site. The two models forms are similar but using cross sites correlations in
the first one , while the second one uses the cross variables correlations. Much progress had been
made principally in the last 20 years to come up with theoretical frameworks for spatial analysis
Khalili , 2007.Some models, such as space–time models have been developed to regionalize the
weather generators. In these models, the precipitation is linked to the atmospheric circulation
patterns using conditional distributions and conditional spatial covariance functions Lee et al.,
2010. The multi-site weather generators presented above are designed using relevant statistic
information. Most of these models are either complicated or some are applicable with a certain
conditions. In real situation both cross variables and cross sites correlation may exist between
different hydrological variables at different sites. There exist in the literature some relatively
recent some trials to account for the spatial variation in multi-sites. Calder, 2007, had proposed
a Bayesian dynamic factor process convolution model for multivariate spatial temporal processes
and illustrated the utility of the approach in modeling large air quality monitoring data. The
underlying latent components are constructed by convolving temporally-evolving processes
defined on a grid covering the spatial domain and include both trend and cyclical components.
As a result, by summarizing the factors on a regular spatial grid, the variation in information
about the pollutant levels over space can be explored. Al-Suhili et al., 2010, had presented a
multisite multivariate model for forecasting different water demand typesat different areas in the
city of Karkouk, north Iraq. This model first relate the each demand type with explanatory
variables that affect its type, using regression models, then obtaining the residual series of each
variable at each site. These residual are then modeled using multisite Matalas models for each
type of demand. These models were coupled with the regression equation to form the multisite
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multivariate variation. The last two cited research are those among the little work done on
forecasting models of multi-sites multivariate types. However these model are rather
complicated, and/or do not model the process of cross site and cross variables correlation
simultaneously, which as mentioned above the real physical case that may exist. Hence
researches are further required to develop a simplified multisite multivariate model. In this
research a new straightforward multisite-multivariate approach is proposed to develop such a
model that describe the cross variables and cross sites correlation structure in the forecasting of
multi variables at multi sites simultaneously. This model was applied to a case study of monthly
data of two hydrological variables, rainfall and evaporation at three sites located north Iraq,
Sulaimania, Dokan, and Darbandikhan.
2. THE MODEL DEVELOPMENT
The multivariate multisite model developed herein, utilizes single variable lag correlations,
cross variables lag-correlations, and cross sites correlations.
In order to illustrate the model derivation consider Fig.1 shown. This figure illustrates the
concept of two variables, two sites and first order model. This simple form is used to simplify the
derivation of the model. However, then the model could be easily generalized using the same
concept. For instant, Fig. 2 is a schematic diagram for a multivariate multisite model of two
variables, three sites and first order time. The concept is that if there will be two-variables, two
sites, and one time step (first order), then there will exist (8) nodal points. Four of these represent
the known variable, i.e. values at time (t-1); the other four are the dependent variables, i.e. the
values at time (t). As mentioned before Fig. 1 shows a schematic representation of the developed
multisite multivariate model and will be abbreviated hereafter as MVMS (V, S ,O),where V:
stands for number of variables in each site , S: number of sites , and O : time order, hence figure
(1) can be designated as MSMV (2,2,1), while Fig. 2 MVMS (2,3,1).
This model can be extended further to (v-variables) and / or (s-sites) and / or (o- time) orders as
will be shown later .The model concept assume that each variable dependent stochastic
component at time t can be expressed as a function of the independent stochastic component for
all other variables at time (t), and those dependent component for all variables at time (t-1) at all
sites. The expression is weighted by serial correlation coefficient, cross-site cross-correlation
coefficient, cross-variable cross coefficient and cross-site, cross-variable correlation coefficient.
In addition to that; the independent stochastic components are weighted by the residuals of all
types of correlations. These residual correlations are expressed using the same concept of
autoregressive first order model (Markov chain). Further modification of this model is to use
relative correlation matrix parameters by using correlation values relative to total sum of
correlation for each variable, and the total sum of residuals as a mathematical filter ,as will be
shown later.
A model matrix equation for first order time lag, O=1, number of variables=V, and number of
sites=S, could be put in the following form:
[ ϵt]v*s,1 = [ρ]v*s,v*s* [ϵt-1] v*s,1 + [σ ] v*s,v*s * [ξt]v*s,1
(1)
Which for v=2,s=3,and =1
[ ϵt]6,1 = [ρ]6,6* [ϵt-1] 6,1 + [σ ] 6,6 * [ξt] 6,1
(2)
Where :
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(3)
t
= [ϵt-1] 6,1
(4)
t-1
= [ξt] 6,1
(5)
‫ــــ ــــ ـــ‬
t
=[
(6)
= [σ ] 6,6
55
(7)
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where:
ρ1,1 = ρ [(x1, x1), (s1, s1), (t, t-1) ]= population serial correlation coefficient of variable 1 with
itself at site 1 at site 1, for time lagged 1
ρ1,2= ρ [(x1, x2), (s1, s1), (t, t-1) ]= population cross correlation coefficient of variable 1 at site 1
with variable 2 at site 1, for time lagged 1
ρ1,3= ρ [(x1, x1), (s1, s2), (t, t-1) ]= population cross correlation coefficient of variable 1 at site 1
with variable 1 at site 2, for time lagged 1
ρ1,4= ρ [(x1, x2), (s1, s2), (t, t-1) ]= population cross correlation coefficient of variable 1 at site 1
with variable 2 at site 2, for time lagged 1
ρ1,5= ρ [(x1, x1), (s1, s3), (t, t-1) ]= population cross correlation coefficient of variable 1 at site 1
with variable 1 at site 3, for time lagged 1
ρ1,6= ρ [(x1, x2), (s1, s3),(t,t-1) ]= population cross correlation coefficient of variable 1 at site 1
with variable 2 at site 3, for time lagged 1,the definition continues… , finally
ρ6,6= ρ [(x2, x2), (s3, s3), (t, t-1) ]= population serial correlation coefficient of variable 2 at site 3
with variable 2 at site 3, for time lagged 1.
The designated (ρ i,j ) is used for simplifying .That is variables at site 1 ,as 1, and 2,for this
model ( in general to 1,2,…v),then for variables at site 2,as 3 ,and 4 (in general from v+1 to 2v
and so on) hence (r1,v+1) stands for the correlation between variable 1 at site 1,and variable 1 at
site 2 and so on.
ϵ: is the Stochastic dependent component.
ξ: is the Stochastic independent component.
σ i,j : are the residual of the correlation coefficient ρi,j.
The matrix, Eq. (2) can be written for each term, for example, for the first term:
ϵ(1,s1,t) = ρ1,1 * ϵ(1,s1,t-1) + ρ1,2 * ϵ(2,s1,t-1) + ρ1,3 * ϵ(1,s2,t-1) + ρ1,4 * ϵ(2,s2,t-1)+
ρ1,5 * ϵ(1,s3,t-1) + ρ1,6 * ϵ(2,s3,t-1) +σ 1,1 * ξ(1,s1,t) + σ 1,2 * ξ(2,s1,t) + σ 1,3 * ξ(1,s2,t) + σ 1,4 *
ξ(2,s2,t) + σ 1,5 * ξ(1,s3,t) + σ 1,6 * ξ(2,s3,t)
(8)
Similar equations could be written for the other variables. The correlation coefficient in each
equation is filtered by a division summation filter, as in the following equation:
∑
.
(9)
Where
is the relative correlation coefficient of row i and column j of the matrix in
eq.(6). The corresponding σ values are estimated using the following equation:
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√
(10)
Then these σ i,j are also filtered using equation similar to eq.(9) as follows:
(11)
∑
Then the model matrix equation is the same as that appear in Eq.(2), replacing ρi,j values by the
corresponding relative values
in the matrix Eq.(6), and σi,j with the corresponding relative
values σri,j in the matrix Eq.(7) . The model can be generalized to any number of variables and
number of sites.
3. THE CASE STUDY AND APPLICATION OF THE MODEL.
In order to apply the new developed (MVMS) model explained above the Sulaimania
Governorate was selected as a case study. Sulaimania Governorate is located north of Iraq with
total area of (17,023 km2) and population, 2009. 1,350,000. The city of Sulaimania is located
(198) km north east from Kurdistan Regional capital (Erbil) and (385) km north from the Federal
Iraqi capital (Baghdad). It is located between (33/43- 20/46) longitudinal parallels, eastwards and
31/36-32/44 latitudinal parallels, westwards. Sulaimania is surrounded by the Azmar Range,
Goizja Range and the Qaiwan Range from the north east, Baranan Mountain from the south and
the Tasluje Hills from the west. The area has a semi-arid climate with very hot and dry summers
and very cold winters. Barzanji, 2003.
The variables used in the model among other meteorological recoded data are (rainfall and
evaporation) for monthly model as a two main variables that are expected to be useful for
catchment management and runoff calculation. Data were taken from three meteorological
stations (sites) inside and around Sulaimania city, which are Sulimania, Dokan dam, and
Darbandikhan dam meteorological stations. Dokan dam metrological station is located (61 km)
north east, and Darbandikhan dam metrological station is located (55 km) south east of
Sulaimania city. While Dokan dam meteorological station is located (114 km) north east of
Darbandikhan dam metrological station .The sites coordinates are given in Table 1, Barzinji
,2003.The Satellite image of the locations of the three stations showed in Fig.3.
The model was applied to the data of the case study described above. The length of record for the
two variables and the three stations is (27) years, (1984-2010). The data for the first (22), (19842005) years were used for model building, while the left last 5 years data were used for
verification,(2006-2010). It is worth to mention that the data are on monthly basis. Moreover
since the analysis includes the rainfall as a variable which has zero values for June, July, August
and September, in the selected area of the case study, these months are excluded from the
analysis. Hence the model was built for the continuous period from October to May.
In order to give a general view for the data used the descriptive statistics (Mean, Standard
deviation Sd, Coefficient of Skewness Cs, Coefficient of kurtosis Ck, Maximum Max, Minimum
Min) were calculated for rainfall and evaporation of Sulaimania, Dokan dam, and Darbandikhan
dam meteorological stations and are shown in Table 2.
Before proceeding with the modeling process the data series should be checked for their
homogeneity . The split sample test suggested by Yevjevich, 1972, was applied for this purpose
for each data series to test the homogeneity both in mean and standard deviation values.
Different sizes of the subsamples were used for dividing the data sample into two subsamples
with (n1,and n2) as number of years for subsample one and subsample 2 respectively. That is
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(n1:n2) as (1,26),(2,25),(3,24), and so on. The split sample test result on estimated t-values that
was compared with the critical t-value. If the t-value estimated is greater than the critical t-value
then the data series is considered as non-homogeneous, Yeijevich, 1972 , and thus this nonhomogeneity should be removed. The results of this test had showed that there are some different
subsamples splitting (n1:n2) values that exhibit non- homogeneity exist, however these cases that
gives the maximum t-test values were considered for each of the 6- data series.Table.3 shows
these results, which indicates that non-homogeneity is exist in Sulaimania evaporation, Dokan
rainfall, and Derbendikhan evaporation data series, while the series of the other variables are
homogeneous. To remove this non-homogeneity the method suggested by Yeijevich,1972 was
used that using the following equation:
(12)
Where,
Hi,j : is the homogenized series at year i,month j of the first sub-sample (old).
Xi,j : is the original series at year i, month j, of the first sub-sample .
A1, B1: are the linear regression coefficients of the annual means.
A2,B2 : are the linear regression coefficients of the annual standard Deviations.
Mean2,Sd2 : are the overall mean and standard deviation of the second sub-sample.
This implies that the data is normalized according to the second sub-sample, i.e., the most recent
one which is the correct way for forecasting. Table.4 shows the values of the of
Mean2,Sd2,A1,B1,A2,and B2, for the three non-homogeneous series.
The homogenized data were then retested to make sure that the transformation applied in
Eq.(12), had removed the non-homogeneity. Table.5 shows these results which ensure that the
data series are all now homogeneous.
The next step in the modeling process is to check and remove the trend component in the data if
exist. This was done by finding the linear correlation coefficient(r) of the annual means of the
homogenized series, and the t-value related to it. If the t-value estimated is located in the r=0
hypothesis rejecting area t> + or - critical t-value of 2.83 then trend exist otherwise it is not. The
following equation is used to estimate the T-values.
√
T= √
(13)
Where
Table 6 shows these results, which indicate the absence of the trend component in all of the data
series of the six variables.
Before proceeding into the modeling process the data should be normalized to reduce the
skewness coefficient to zero. The well-known Box-Cox transformation Box and Jenkin , 1976
was used for this purpose as presented in the following equation:
(14)
Where:
µ : is the power
α : is the shifting parameter.
XN : is the normalized series.
Table.7 shows the coefficients of the normalization transformation of all of the six series. The
shifting parameter is selected to ensure avoiding any mathematical problem that may occur due
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to the fraction value of the power µ. The power value is found by trial and error so as to select its
value that reduce the skewness to almost zero value. Table 8 shows the statistical properties of
the series before and after normalization, which indicate that the skewness coefficients are
reduced to almost zero a property of the normal data.
The next step in the modeling process is to remove the periodic component to obtain the
stochastic dependent component of the series, which is done by using Eq.(15), as follows:
=
(15)
Where:
ϵi,j : is the obtained dependent stochastic component for year i, month j.
Xbj : is the monthly mean of month j of the normalized series XN.
Sdj : is the monthly standard Deviation of month j of the normalized series XN.
Table 9 shows the monthly means and monthly standard deviations of the normalized data series
XN. The ϵi,j obtained series are then used to estimate the Lag-1 serial and cross correlation
coefficients ρi,j , and σi,jof matrix Eqs.(6) and (7) respectively, which then used to estimate ρri,j
and σri,j using Eqs.(9), and (11), respectively..
4. RESULTS AND DISCUSSION
The developed model above is used for data forecasting, recalling that the estimated parameters
above are observed using the 22 years data series (1984-2005). This model will be used to
forecast data for the next 5- years (2006-2010) since the data available are up to 2010, that could
be compared with the observed series available for these years, for the purpose of model
validation.
The forecasting process was conducted using the following steps:
1. Generation of an independent stochastic component (𝝃) using normally distributed generator,
for 5 years,i.e., (5*12) values.
2. Calculating the dependent stochastic component (ϵi,j) using Eq. (2) and the matrices of ρri,j and
σri,j as shown in Eqs. (9) and (11), respectively.
3. Reversing the standardization process by using the same monthly means and monthly standard
deviations which were used for each variable to remove periodicity using Eq. (15) after
rearranging.
4. Applying the inverse power normalization transformation (Box and Cox) for calculating unnormalized variables using normalization parameters for each variable and Eq.(14).
In most forecasting situation, accuracy is treated as the overriding criterion for selecting a model.
In many instance the word “accuracy” refers to “goodness of fit,” which in turn refers to how
well the forecasting model is able to reproduce the data that are already known. The model
validation is done by using the following steps:
1. Checking if the developed monthly model resembles the general overall statistical
characteristics of the observed series.
2. Checking if the developed monthly model resembles monthly means, monthly standard
deviations using t-test for the means and F-test for the standard deviation.
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Furthermore the performance of the new multi-variables multi-sites model developed herein was
compared with the well-known single variable single site model, and multi-variables single site
model (MATALS model). This performance was made to investigate whether the new model can
produce better forecasted data series. For purpose of comparison of different forecasting models
performance, the Akaike (AIC), test given by the following equation:
(16)
Where:
n: is the number of the total forecasted values .
K: number of parameters of the model plus 1.
Rss: is the sum of square error between the forecasted value and the corresponding observed
value.
For each site and variable three sets of data are generated. The overall statistical characteristics
are compared with those observed, for each of the generated series. Table 10 shows these
comparisons. For all variables and sites the generated sets resemble the statistical characteristics
not exactly with the same values of the observed series but sometimes larger or smaller but
within an acceptable range. Table 11 shows the t-test and F-test summary for all of the variables
and sites. As it is obvious from the results of these tables, that the generated series succeed in (ttest) for all of the monthly means, except for two months for Sulaimania rainfall, i.e. overall
succeed percent of (98.6%). This indicates that the model is successfully resembled the monthly
means values, with excellent accuracy.
Based on (F-test) which seek the variance differences between the observed and generated series;
the success percentage ranking of the generated series was: the best being for Sulaimania rainfall
(96%), followed by Darbandikhan evaporation (88%), Darbandikhan rainfall (83%), Dokan
evaporation (83%), Dokan rainfall (71%), and finally Sulaimania evaporation (67%). The overall
success percentage was (81%). These results of the F-test indicate that the model was
successfully resembled the monthly standard deviations, with a very good accuracy. As
mentioned above for purpose of the comparison of the model performance with the available
forecasting models, the Akaike , 1974 test was used. Before that six single variable single site
models were developed, one for each variable, and three single variable multi-site models,
Matalas ,1967 one for each site. These models were then used for forecasting monthly data for
the same period (2006-2010), forecasted by the developed model.
Table.12 shows the Akaike test results for all of the forecasted variables, in each sites, obtained
using these model and those obtained by the developed model. It is obvious that the developed
model had produced for most of the cases the lowest test value, i.e, the better performance. Even
though for some cases it has higher test value than the other models, but for these cases it is
observed that a very little differences are exist between these test values and the minimum
obtained one.
5. CONCLUSIONS
From the analysis done in this research, the following conclusion could be deduced:
1- The model parameters can be easily estimated and do not require any extensive
mathematical manipulation.
2- The model can preserve the overall statistical properties of the observed series with high
accuracy.
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3- The model can preserve the monthly means of the observed series with excellent
accuracy, evaluated using the t-test with overall success (98.6%).
4- The model can preserve the monthly standard deviations of the observed series with a
very good accuracy, evaluated using the F-test with overall success (81%).
5- The comparison of the model performance with the single variable single site and the
multi-site single variable models, using the Akaike tset had proved that the developed
model had proved better performance in the most cases. Moreover for those less cases
where other models had the better performance; the test value of the developed model is
slightly higher than the minimum value.
REFERENCES
Al-Suhili R.H., Al-Kazwini, M. J., and Arselan, C. A., Multivariate Multisite Model
MV.MS. Reg. for Water Demand Forecasting , Eng. and Tech. Journal Vol. 28, No. 13
,2010, pp 2516-2529.
Akaike, H., 1974, A New Look at the Statistical Model Identification , IEEE T. Automat.
Contr., 19(6), 716–723.
Barzinji K. T., 2003, Hydrogic Studies for Goizha Dabashan and Other Watersheds in
Sulimani Governorate , M.Sc. thesis submitted to the college of Agriculture, University of
Sulaimani
Box, G.E., and Jenkins, G. M. (1976), Time Series Analysis and Control, San Francisco,
California: Holden-Day,Inc.
Calder C.A., 2007, Dynamic Factor Process Convolution Models for Multivariate SpaceTime Data with Application to Air Quality Assessment, J. Environ.Ecol. Stat. Vol.14: 229247.
Khalili M, Leconte R. and Brissette F., 2007, Stochastic Multisite Generation of Daily
Precipitation Data Using Spatial Autocorrelation, J Hydrometeorology, Vol.8, P 396-412
Lee Seung-Jae and Wents E. A., 2010, Space-Time Forecasting Using Soft Geostatitiscs:
A Case Study in Forecasting Municipal Water Demand for Phhonex, Arizona , Stoch
Environ Risk Assess 24: pp 283- 295
.
Matalas N.C., 1967, Mathematical Assessment of Synthetic Hydrology, Water Resoures 3:
937-945.
Richardson C. W. and Wright D. A., 1984, WGEN: A Model for Generating Daily
Weather Variables, United States Department of Agriculture, Agriculture Research
Service ARS-8
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Tobler W., (1970) , A Computer Movie Simulating Urban Growth in the Detroit Region,
Economic Geography, 46(2): 234-240.
Wilks D. S., 1999, Simultaneous Stochastic Simulation of Daily Precipitation,
Temperature and Solar Radiation at Multiple Sites in Complex Terrain, Elsevier,
agricultural and forest meteorology 96:85-101.
Yevjevich, V. M., The Structure of Hydrologic Time Series, Fort Collins, Colorado State
University, 1972.
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Figure 1. Schematic representation of the two variables two sites multi variables
multisite model.
Figure 2. Schematic representation of the two variables three sites multi variables
multisite model.
Table 1. North and east coordinates of the metrological stations selected for analysis.
Metrological station
N
E
o
'
"
o
Sulaimania
35 33 18
45 27' 06"
o
Dokan
35 57’ 15”
44o 57' 10"
Derbenikhan
35o 06' 46"
45o 42' 23"
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Table 2. Descriptive statistics of the original data series.
Skewne
ss
Kurtosi
s
Max
Min
69
0.9
0.7
354
0.1
73
63
1
3
310
0.1
120
70
1
1
415
36
106
51
1
-1
220
40
93
80
1
0.7
416
0.1
64
56
1
2
262
1
116
68
0.9
-0.1
322
24.9
101
60
1
1
284
35
78
67
1.2
1.3
326
0.4
69
59
1
1
247
0
134
69
0.7
-0.3
341
34.1
111
62
1
0.1
276
37
S.D.
Table 3. Test of homogeneity results, with tc=2.38, at 95% significant level.
Yes
1.7
23
5
Yes
2.5
6
21
6
No
2.91
22
5
No
2.7
6
15
12
No
2.77
24
3
No
2.3
1
25
2
Yes
1.77
23
4
Yes
2.3
5
22
Yes
2.05
6
21
Yes
3.2
5
18
9
No
0.93
17
10
Yes
88
Homo.
12
N2
15
N1
2.0
8
N2
t-statistic
Test for S. D.
Homo.
Sulaimania
Rainfall(mm)
Sulaimania
Evapor.(mm)
Dokan
Rainfall(mm)
Dokan
Evapor.(mm)
Derbendkan
Rainfall(mm)
Derbendkan
Evapor.mm)
N1
Variable
t-statistic
Test for Means
Min
S.D.
91
Mean
Mean
Sulaimania
Rainfall(mm)
Sulaimania
Evapor.(mm)
Dokan
Rainfall(mm)
Dokan
Evapor.(mm)
Derbendkan
Rainfall(mm)
Derbendkan
Evapor.(mm)
2006-2010
Skewne
ssCs
Kurtosi
s
Max
1984-2005
Variable
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Table 4. Coefficients of non-homogeneity removal.
Variable
Sulaimania
Evapor.(mm)
Dokan
Rainfall(mm)
Derbendkan
Evapor.mm)
Mean2
S.D.2
A1
B1
A2
B2
106.3
50.62
127.297
-0.602
62.958
0.7065
55.96
41.33
101.91
-0.815
79.314
-0.319
117.5
70.45
131.18
0.4
69.93
-0.229
Table 5. Re- test of homogeneity, with tc=2.38, at 95% significant level.
Yes
1.7
23
5
Yes
1.69
26
1
Yes
1.17
9
18
Yes
1.92
1
26
Yes
1.61
2
25
Yes
2.31
25
2
Yes
1.77
23
4
Yes
2.3
5
22
Yes
2.05
6
21
Yes
1.08
26
1
Yes
1.33
8
19
Yes
Homo.
12
N2
15
N1
2.08
N2
t-statistic
Test for S. D.
Homo.
Sulaimania
Rainfall(mm)
Sulaimania
Evapor.(mm)
Dokan
Rainfall(mm)
Dokan
Evapor.(mm)
Derbendkan
Rainfall(mm)
Derbendkan
Evapor.mm)
N1
Variable
t-statistic
Test for Means
Table 6.Test of trend results, with tc=2.38, at 95% significant level.
Variable
Sulaimania
Rainfall(mm)
Sulaimania
Evapor.(mm)
Dokan
Rainfall(mm)
Dokan
Evapor.(mm)
Derbendkan
Rainfall(mm)
Derbendkan
Evapor.mm)
T for means
T for S.D.
0.16
0.023
0.21
1.06
0.2
0.4
0.04
0.13
1.04
0.04
0.28
0.41
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Table 7. Coefficients of the normalization transformation.
Variable
Sulaimania
Rainfall(mm)
Sulaimania
Evapor.(mm)
Dokan
Rainfall(mm)
Dokan
Evapor.(mm)
Derbendkan
Rainfall(mm)
Derbendkan
Evapor.mm)
Power µ
Shifting α
0.47
1
-0.52
0
0.27
0
-0.054
0
0.359
0
0.232
0
Table 8. Statistical properties before and after the normalization transformation.
Mean
S.D.
Skewness
Kurtosis
91
69
0.9
0.7
14.36
6.84
-0.15
-0.49
106
49
1
0.7
1.8
1.32
0.1
-1.1
54.8
42.9
0.9
0.5
6.5
2.5
-0.1
-1.0
116
68
0.9
-0.1
4.1
0.5
0.0
-0.9
93
80
1
0.7
9.2
4.5
-0.12
-0.61
118.3
71.3
0.75
-0.27
8.3
1.8
-0.04
-0.79
S.D.
Kurtosis
Sulaimania
Rainfall(mm)
Sulaimania
Evapor.(mm)
Dokan
Rainfall(mm)
Dokan
Evapor.(mm)
Derbendkan
Rainfall(mm)
Derbendkan
Evapor.(mm)
Mean
Variable
After Norm.
Skewness
Before Norm.
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Table 9. Monthly means and standard deviations for the dependent stochastic
component.
Variable
Sulaimania
Rainfall
Means
Sulaimania
Rainfall
S.D
Oct.
Nov.
Dec.
Jan.
6.923738 15.95873 18.27623 17.95162
Feb.
16.6502
Mar.
Apr.
May
17.02956 15.15592 8.927809
5.851398 7.895653 6.532181 5.975568 5.221715 5.869138 5.521562 5.782993
Sulaimania
Evapor.
Mean
1.790015 1.750803 1.715869 1.707902 1.715362 1.756555 1.779253 1.810782
Sulaimania
Evapor.
S.D.
0.010111 0.016859 0.019150 0.022393 0.013306 0.017357 0.016122 0.010803
Dokan
Rainfall
Mean
3.908560 1.816542 3.908560 1.816542 3.908560 1.816542 3.908560 1.816542
Dokan
Rainfall
S.D.
6.718586 2.294015 6.718586 2.294015 6.718586 2.294015 6.718586 2.294015
Dokan
Evapor
Mean
4.56241
Dokan
Evapor.
S.D.
0.091936
4.56241
0.091936
4.56241
0.091936
4.56241
0.091936
4.006939 0.176918 4.006939 0.176918 4.006939 0.176918 4.006939 0.176918
Derbendkan
Rainfall
Mean
4.932498 9.747093 11.70001 11.72048 11.67984 11.31086
Derbendkan
Rainfall
S.D.
3.35148
Derbendkan
Evapor.
Mean
10.02914 7.414099 6.914041 6.468882 6.859431 8.805194 9.050721 10.86809
Derbendkan
Evapor.
S.D.
0.599518 0.585723 2.012912
7.90416
4.803818
4.540729 4.442926 3.669128 2.898333 3.798071 2.871659
2.83866
1.68868
999
0.775737 1.093621 0.677337 0.609332
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Table 10. Statistical properties of observed and forecasted rainfall series (2006-2010).
Variable
Min
Max
Kurtosis
Skewness
S.D.
Mean
Sul. Obs. R
0.1
310
3
1
63
73
Sul. Gen 1 R
2.3
360.1
-0.6
0.4
66.1
75.1
Sul. Gen 2 R
2.5
282.1
0.1
0.7
64.2
72.7
Sul. Gen 3 R
6.8
248.3
-0.2
0.5
65.5
75.3
Dok. Obs. R
1
262
2
1
56
64
Dok. Gen 1 R
3
261
0.5
0.7
54
68
Dok. Gen 2 R
3
246
-0.1
0.7
52
58
Dok. Gen 3 R
6
266
0.2
0.7
49
65
Der. Obs. R
0.1
247
1
1
59
69
Der. Gen 1 R
0.9
375
-0.4
0.7
55
71
Der. Gen 1 R
1.4
243
0.1
0.9
51
66
Der. Gen 1 R
6.0
241
-0.1
0.7
53
78
Sul. Obs. E
40
220
-1
1
50
105
Sul. Gen 1 E
43
220
0.1
1.0
52
94
Sul. Gen 2 E
49
255
-0.1
1.0
53
101
Sul. Gen 3 E
53
227
0.0
0.9
48
109
Dok. Obs. E
35
262
1
1
60
101
Dok. Gen 1 E
27
276
-0.2
0.9
61
100
Dok. Gen 2 E
35
318
-0.1
0.9
68
105
Dok. Gen 3 E
37
279
-0.3
0.9
62
109
Der. Obs. E
37
276
0
1
62
111
Der. Gen 1 E
10
270
-0.4
0.7
62
95
Der. Gen 1 E
19
303
-0.5
0.6
67
123
Der. Gen 1 E
16
262
-0.5
0.7
60
108
R: Rainfall, E: Evaporation.
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Table 11. Percentage success of T-test for monthly means and F-test for monthly
standard deviations for three generated series for each variable, for years (2006-2010).
Variable
Sulaimania
Rainfall(mm)
Sulaimania
Evapor.(mm)
Dokan
Rainfall(mm)
Dokan
Evapor.(mm)
Derbendkan
Rainfall(mm)
Derbendkan
Evapor.mm)
Over all
% Success in T-test
% Success in F-test
97.22
96
100
67
100
71
100
83
100
83
100
88
98.60
81
Table 12. Comparison between the minimum Akaike test values obtained by the
developed model, the multi-variable single site model, and the single variable single
site model, for three generated series for each variable, by each model, for years
(2006-2010).
Sulaim.
Sulaim.
Dokan
Dokan
Derbend. Derbend.
variable
Rainfall
Evap.
Rainfall
Evap.
Rainfall
Evap.
The
Developed
1,544
1,189
1,438
1,264
1,535
1,404
Model
Multi
Variable
1,600
1,179
1,421
1,253
1,628
1,423
Multi Sites
Model
Single
Variable
1,606
1,191
1,463
1,214
1,550
1,420
Single Site
Model
999
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Journal of Engineering
Removal of Water Turbidity by using Aluminum Filings as a Filter
Media
Dr. Abeer Ibrahim Alwared
Instructor
College of l Engineering / University of Baghdad
[email protected]
Suhair Luay Zeki
Ministry of Water Resources
[email protected] m
ABSTRACT
T he ability of using aluminum filings which is locally
solid waste was tested as a
mono media in gravity rapid filter. The present study was conducted to evaluate the
effect of variation of influent water turbidity (10, 20and 30 NTU); flow rate(30, 40,
and 60 l/hr) and bed height (30and60)cm on the performance of aluminum filings filter
media for 5 hours run time and compare it with the conventional sand filter. The
results indicated that aluminum filings filter showed better perform ance than sand
filter in the removal of turbidity and in the reduction of head loss. Results showed that
the statistical model developed by the multiple linear regression was proved to be
valid, and it could be used to predict head loss in aluminum filings filter and sand
filter with R 2 equal to 0.94 and 0.968 respectively.
Key words: water treatment turbidity, filtration, aluminum filings, sand .
‫ازالت عكىرة الوياه باست عوال برادة االلونيىم كىسط ترشيح‬
ً‫سهير لؤي زك‬
‫ عبير ابراهين هىسى‬.‫د‬
‫هذرس‬
‫كليت الهنذست – جاهعت بغذاد‬
‫وزارة الوى ارد الوائيت‬
‫الخالصت‬
‫حضًٍ انبحث دراست ايكاٍَت اسخخذاو برادة االنًٍُٕو كًادِ يرشحّ احادٌت الزانت عكٕرة انًاء يٍ خالل اخخبار كفاءة انًرشح‬
30(‫ساعت ٔ ارحفاع انٕسط‬/‫) نخر‬60 ،40 ،30 ( ٌ‫ ٔحذة عكٕرة) ٔيعذل انجرٌا‬30، 20 ،10(‫نخاثٍر انخغٍر فً عكٕرة انًاء انذاخم‬
5ٔ 0.5( ٍٍ‫) سى عهى يقذار انعكٕرة انخارجت ٔارحفاع عًٕد انًاء ٔيقارَخٓا يع يرشح انريم انخقهٍذي ٔنًذة حرأحج ب‬60 ،
‫ ٔنقذ بٍُج انُخائج اٌ كفاءة يرشح برادة االنًٍُٕو كاَج اعهى يٍ كفاءة انًرشح انريهً كًا اظٓرث انُخائج اٌ ارحفاع‬. )‫ساعاث‬
‫ كًا اسخخذيج انبٍاَاث يٍ اخخباراث‬.)%32-8( ً‫عًٕد انًاء نبرادة االنًٍُٕو كاٌ اقم يًإْ عهٍّ فً حانت انًرشح انريهً بحٕان‬
ٍ‫انخرشٍح نبُاء ًَٕرج إحصائً نذراست حاثٍر انًخغٍراث انًذرٔست عهى ارحفاع عًٕد انًٍاِ باسخخذاو االَحذار انخطً انًخعذد ٔي‬
ً‫خالل يقارَت انُخائج انحقهٍت يع حهك انخً حى انحصٕل عهٍٓا باسخخذاو انًُٕرج االحصائً حى انخٕصم انى كفاءة انًُٕرج االحصائ‬
‫ عهى‬0..68 ٔ 0..4 ‫ حسأي‬R2 ‫بحٍث ًٌكٍ اسخخذايّ نهخُبؤ باحفاع عًٕد انًٍاِ فً يرشح األنًٍُٕو ٔيرشح انريم حٍث كاَج‬
.ً‫انخٕان‬
.‫ ريم‬، ‫ برادة االنًٍُٕو‬، ‫ حرشٍح‬، ‫عكٕرة‬، ِ‫ يعانجت انًٍا‬: ‫الكلواث الرئيست‬
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1. INTRODUCTION
One of the many challenges faced in developing world is the issue of waste management.
According to the US Army Corps. of Engineers, USACE, 1995. “Aluminum has excellent
corrosion resistance in a wide range of water and soil conditions because of the tough oxide film
that forms on its surface.
The Aluminum Association, 2005. states, “Unless exposed to some substance or condition which
destroys this protective oxide coating, the metal remains resistant to corrosion. Aluminum is highly
resistant to weathering, even in many industrial atmospheres, which often corrode other metals. It is
also resistant to many acids.”
The surface water is the main source for water supply in most developing countries and in many
parts of the world, river water that can be highly turbid, is used for drinking purposes. Access to
improved drinking water is unavailable to an estimated 884 million people in the world most of
who live in rural dispersed and often remote communities in developing countries
WHO/UNICEF, 2010. As identified by the United States Environmental Protection Agency
(USEPA), turbidity is a measure of the cloudiness of water; it is used to indicate water quality. The
main problem in using surface water as a source of water supply is high concentration of clay and
suspended solids, organic compounds and disease-causing microorganisms (such as viruses,
parasites and some bacteria) which can cause symptoms such as nausea, cramps, diarrhea, and
provide food and shelter for pathogens ,WHO, 2007. The permissible limit for treated water in Iraq
is 5 NTU , according to Iraqi standards, 2001.
Filtration is the most common method to remove clay and suspended solids, in filtration process,
water is purified by passing through a bed of porous media which cause the retention of suspended
matters within it. Although the existing granular filter media such as sand is sufficient to treat turbid
water, discovering an alternative filter media from local source is also highly essential and are
becoming popular since it will help to reduce the cost of treatment, as it can be processed and
produced locally, and of their better removal efficiency as compared to conventionally used media
Jusoh et al., 2006 .
Jasim ,1977 examined the efficiency of rice shell and crushed date stone as an alternative materials
due to their availability in large quantities in Iraq, and concluded that these materials can be utilized
as a filtering media rather than as animal feed.
Al-Anbari,1997 selected suitable and durable locally filter media. The author tested the
lightweight material like (porcelanite rocks and brunt kaolinite), and a heavy weight media like
(goethite rock). For single media filter, porcelanite and kaolinite gave better results in turbidity
removal efficiency and net water product value than sand medium.
Tang et al., 2006 evaluated the performance of crumb rubber as filtering material for ballast water
treatment. It was found that crumb rubber is an excellent filter media for downward granular media
filters in comparison to traditional granular media filters, a substantial reduction in turbidity was
achieved, no clear relationship between filter depth and turbidity removal efficiency was found,
higher filtration rate resulted in a lower turbidity removal efficiency.
Juosh et al.,2006 used palm shell as single and dual media filter. Palm shell is one of the industrial
wastes that are abundantly available. Result suggests that all the filters are capable of producing
water with acceptable turbidity unit (<1 NTU).
Nasser, 2010 investigated the ability of using crushed glass solid wastes as mono media with sand
in the filtration process. The results indicated that the glass filters had better turbidity removal
104
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Journal of Engineering
efficiencies with a reduction of about 50% in washing water was required to wash the glass filters.
Also glass filters were slower in the development of head losses.
Shubir, 2011 investigated the ability of using crushed plastic solid wastes, whose density less than
that of water, in water filtration. The results indicated that the single plastic filters and the dual
filters produced water of the same (high) quality as the sand filter. Also, it showed that plastic filters
were slower in development of head losses and they have longer running time than the sand filters.
The main objective of this work is to evaluate the performance and effectiveness of sand filters by
utilizing aluminum filings as filter media which is a locally available solid waste material .
2. EXPERIMENTAL WORK
The experimental work of this study was based upon the use of packed bed filtration pilot plant for
the removal of water turbidity by using different types of solid wastes as a filter media (aluminum
filings and sand) at different flow rate , initial turbidity and bed height The experimental apparatus
is shown in Fig. 1. It consisted of two galvanized cylindrical tanks of capacity 70 L; Perspex filter
column of 7.5 cm inner diameter and 150 cm height designed and built to run with down flow
direction according to ,AWWA Manual, 2000. Calibrated flow meter was used to control the flow,
with flow range of (10-100 l/hr). Four glass tubes fitted on a board was used to record the height of
water at different depths for each filter. Two types of filter media were used aluminum filings as a
locally available solid waste and conventional sand filter media, Table 1. show the characteristics
of these filter media.
The aluminum filings used is flat shaped, 100% recycled from solid wastes. It is washed and sieved
to obtain grain sizes of (0.6-1) mm in diameter
The filter was operated on the principle of constant flow rate and variable head loss mode. 70 liter
of turbid water (10, 20, or 30 NTU) was pumped through the flow meter at different flow rates (30,
40, or 60 l/hr). This flow range was chosen to simulate the rapid filter flow rate in most water
treatment plants. Two different bed heights were studied 30 and 60 cm for each experiment.
Samples of the filtered water were taken every (30 minutes) during the run of 5 hours. The water
level in the piezometers was recorded at the starting of each run and at fixed time intervals (each 30
minutes) to determine the head loss along the filter depth.
Turbidity was measured by a portable turbidity meter (Hanna instruments, HI 93703). The
recorded level had accuracy of (0.5) NTU. The values of the available head were read by using the
piezometers at fixed time intervals. PH value was measured for every sample and it was found that
it was within the PH value for tap water.
Large quantity of kaolin was added to 10 liter preparation tank, shaken well, and left for 15 min in
order to let larger suspended solids settle under the influence of gravity, and to obtain turbidities of
(10, 20 , 30) NTU , then it is transferred to the storage tank. Turbid water (10, 20, 30) NTU from
the storage tank was pumped through flow meter at different flow rates (30, 40, 60) l/hr, this flow
range was chosen to simulate the rapid filter flow rate to the filter column. The water level in the
piezometers were recorded at the starting of each run and at fixed time intervals (each 30 minutes)
to determine the head loss along the filter depth. Samples of the filtered water were taken every (30
minutes) during the run of 5 hours. The experimental work was achieved in the Environmental
Engineering Department/ Baghdad University.
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3. RESULTS AND DISCUSSION
3.1 Effect of Influent Turbidity
Three different influent turbidities were tested in this study (10, 20, and 30 NTU), during each run
the flow rate and bed depth were kept constant. Fig.2 illustrates the effect of influent turbidity on
the turbidity removal efficiency. It can be seen from this figure that sand has lower turbidity
removal efficiency compared with aluminum filings filter. It is obvious that greater porosity value
yield poorer filtrate quality due to smaller available surface area for deposition , Gronow, 1986. In
this experimental work, best filtrate results were for aluminum filings filter though they had a
higher porosity than sand filter. The flat shape for the aluminum filings gave better results due to
stability of deposits onto flat surfaces, and not critical deposits onto rounded surfaces as in the case
of sand. These results are in good agreement with Jasim, 1977; who found that flat shaped grains
usually perform better than do rounded or worn grains due to their higher stability of sediments.
3.3 Effect of Flow Rate
The flow rate affects the filtrate quality; it is believed to be due to the increase of interstitial
velocity. The interstitial velocity depends on the incoming approach velocity above the filter bed as
well as the porosity , Holdich, 2002.
Three different flow rates were tested in this study (30, 40 and 60) l/hr. During each run influent
turbidity and bed depth were kept constant. Fig.3 shows the effect of flow rate on turbidity removal
efficiency at 10 NTU influent turbidity of each filter type. It can be seen from these figures that
when the flow rate increased removal efficiency decreased, and this is in a good agreement with the
results of Mohammed, 1989 and Degremont, 1991. At high filtration velocity the retained
suspended solids are sheared off from the bed due to the high velocity force
Sundarakumar, 1996.
3.4 Head Loss Variation with Time
In order to study the head loss across the bed. Piezometers were installed at different depths across
the bed. During the filtration process, head loss built up because particles began to fill the void
space in the filter media. The head loss development was increased with increase in influent
turbidity for all filter media types. Figs. 4, 5 and 6 illustrate the relation between the head loss with
time at different depths for each type of filter media and at10 NTU influent turbidity and 60 cm bed
depth. The head loss development for different influent turbidities is shown in Fig.7.
At low filtration velocity, the amount of suspended solids captured within the media is lower than
the high filtration velocity. So in the case of low filtration velocity, the head loss development is
very slow. This phenomenon is common for all media types as can be seen in Fig. 8.
For the same operational conditions and for all media types, sand filter showed the higher head loss
at different depths than aluminum filings filter. This phenomenon is due to the high porosity of
aluminum compared with sand, sustaining a greater load of sediments with lower head losses.
The head loss after five hours of filtration is presented in Table 2 it can be seen from this table that
aluminum filings filter shows less head losses than the sand filter during all runs, filtration rate
impacted head loss substantially. Generally, a deeper filter depth and higher filtration rate resulted
in a higher head loss.
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4. EFFECT OF BED HEIGHT
Two different bed heights were tested in this study (30, and 60) cm, during each run influent
turbidity and flow rate were kept constant. Filter depth appeared to have fairly significant influence
on turbidity removal efficiency for different initial water turbidity. Fig.9 shows the effect of depth
on the removal efficiency. This can be attributed to the availability of more opportunity for particles
to accumulate in higher depth. These accumulated particles act as new collectors until a saturation
state is reached.
5. STATISTICAL ANALYSIS
A total filtration data sets (two types of filter media (aluminum filings and sand), two media depth
(30 and 60cm) ,three different flow rates (30 , 40 and 60 l/hr ), and three different initial turbidities
(10 , 20, and 30 NTU) were collected and a analysis by using Multiple regression was performed
using excel program for the examination the effects of each parameter on the head loss at the end of
five hours run time.
A mathematical equation was introduced to correlate all of the data obtained using a multiple
regression technique for aluminum filings filter and for and filter is as follows
For aluminum filings:
Head loss(X1) = -28.188+0.0.504 X2 +0.0.472 X3 + 0.723X4
(1)
For sand:
Head loss(X1)= -19.067+0.568 X2+0.344 X3+ 0.9083 X4
(2)
Where: X1= head loss
X2 = flow rate
X3 = bed height and
X4 = influent turbidity
The equations fits the experimental data very well with R2 = 0.94 and 0.968 for aluminum filings
and sand filter respectively, as shown in Fig.10
6. CONCLUSIONS
1. Aluminum filings filter was efficient in turbidity removal as in sand filters. The maximum
turbidity removal efficiency for sand filter was 86% at 40 l/hr filtration rate, while for
aluminum filters as 89% at 30 l/hr filtration rate, 10 NTU influent turbidity, and 60m depth.
2. The maximum head loss for sand was 64.7cm,and aluminum filings was 55.7cm
respectively at 60l/hr filtration rate, 30 NTU influent turbidity, and 60cm depth at the end of
five hours run time.
3. Stability of the sediments in filtration contributed to the shape of the grains forming the
filter bed.
4. Filter depth have fairly significant influence on turbidity removal efficiency, a deeper filter
depth resulted in a higher head loss.
5. The statistical model developed by the multiple linear regression can be used in predicting
head loss in aluminum filings filter and sand filter.
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REFERENCES
 Al-Anbari, R. H.,1997, Selected Alternatives for up Grading Existing Water Treatment Plants,
a Quantitative and Qualitative Improvement, Ph. D. Thesis, University of Technology, Iraq.
 AWWA, 2000, Operational Control of Coagulation and Filtration Processes, Manual of Water
Supply Practices-M37, 2nd edition.
 Degremont, 1999, Water Treatment Handbook, vol. 1, 6th edition, Lavoisier Publishing, Paris.
 Gronow, J. R., 1986, Mechanisims of Particle Movement in Porous Media, Clay Minerals
(1986) 21, 753-767.
 Holdich R., 2002, Fundamentals of Particle Technology, Midland Information Technology and
Publishing, Leicestershire, UK.
 Iraqi Central Organization for Standardization and Quality Control, 2001, Drinking Water
Standards.
 Jasim, L.M., 1977, The Kinetics of Turbid Water Filtration through New Filtering Media for
Rural Treatment', M.Sc. Thesis, University of Baghdad, Iraq.
 Jusoh, A., Giap G., Aini, A., Halim, A., Noor, M. and Zakaria, M., 2006, Comparative
Performance of Single and Dual Media Filters of Sand and Burnt Oil Palm Shell, Journal
Teknologi, vol.45 (F) University Teknologi Malaysia, Pp.43-52.
 Mohammed, O. I., 1989,A Comparison between the Performance of the Conventional and the
Dual-media Filters, M. Sc. Thesis, University of Basrah , Iraq.
 Nasser, N. O. A., 2010, Investigating the Ability of using Crushed Glass Solid Wastes in Water
Filtration, ph. D. Thesis, University of Baghdad, Iraq.
 Shubir, M.D., 2011, Study the Ability of using Crushed Plastic Solid Wastes in Water
Filtration, M. Sc. Thesis, University of Babylon, Iraq.
 Sundarakumar, R., 1996, Pilot Scale Study on Floating Media Filtration for Surface Water
Treatment, M.Sc. Thesis, Asian Institute of Technology School of Environmental and
Resources Development Bankok, Thailand.
 Tang, Z., Butkus, M.A. ,and Xie, Y., F. ,2006, Enhanced Performance of Crumb Rubber
Filtration for Ballast Water Treatment, Chemosphere, 74, Pp.1396-1399.
 The Aluminum Association, 2005, Specifications and Guidelines for Aluminum Structures, 8th
ed., Arlington, VA.
 United States Army Corps of Engineers (USACE), 1995, Design of Seawalls and Bulkheads,
Washington , Pp.1110-2-1614.
 WHO, 2007, Combating Waterborne Disease at the Household Level, World Health
Organization, 729 Geneva.
 WHO/UNICEF, 2010, Progress on Sanitation and Drinking-Water: 2010 Update,
WHO/UNICEF 732 Joint Monitoring Programme for Water Supply and Sanitation, World
Health Organization, 733 Geneva.
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8
8
1.Manometer board 2.Flow meter 3.Wash water
valve 4.Air valve 5 . Filtered water valve
6.Pump 7.Water tank 8.Preparation tank
Figure1. Schematic diagram of experimental apparatus.
Figure 2. Effect of influent turbidity on the turbidity removal efficiency at bed deptht=30, flow rate
30 lit/hr.
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Journal of Engineering
(b)
Figure3. Effect of flow rate variation on turbidity removal efficiency, influent turbidity
=10NTU, bed depth=60 cm.
(a)
(b)
Figure4. Head loss versus time at different heights of the filter at bed depth 60 cm, flow rate = 30
l/hr, turbidity =10 NTU.
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Journal of Engineering
(b)
Figure5. Head loss versus time at different heights of the filters at bed depth 60 cm, flow rate =
40 l/hr, turbidity =10 NTU.
(a)
(b)
Figure6. Head loss versus time at different heights of the filters at bed depth60 cm, flow rate=60
l/hr, turbidity=10 NTU.
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(b)
Figure 7. Head loss versus time at different influent turbidity, flow rate=30 l/hr, filter depth =30
l/hr.
(a)
(b)
Figure 8. Head loss versus time at influent turbidity = 10 NTU , bed depth = 60cm and different
filtration rates.
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(b)
Figure. 9 Impact of bed height on the removal efficiency at different influent and flow rate = 30
l/hr.
(a)
(b)
Figure10. Comparison between actual and predicted head loss.
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Table 1.Characteristics of filter media.
Specific
Effective Uniform
Media
porosity
gravity
size
coefficient
Aluminum
3.08
80%
0.62mm
1.35
filings
Sand
Flow
rate
(l/hr)
30
40
2.66
37%
0.62mm
1.4
Table 2. Head loss for the two filters.
Head loss (cm), bed
Head loss (cm), bed
height 30cm
height 60cm
Influent
Turbidity,
Aluminum
Aluminum
Sand
Sand
NTU
filings
filings
filter
filter
filter
filter
10
19.4
13.2
25.4
17.2
20
25.3
16.5
37.8
31.6
30
32.4
19.9
43.1
34.8
10
26.2
16.7
34.9
25.7
20
31.6
20
44.3
38.9
30
42.7
26.3
53.6
42.1
10
33.2
21.8
43.6
34.1
20
40.3
29.2
51.8
47.6
60
114
Number 7
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20
July
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2014
Journal of Engineering
The Effect of Dynamic Loading on Stresses Induced in Charnley Hip
Prosthesis
Ahmed Abdul Hussain
Mahmood Wael Saeed
MS.C. Student (Mechanical Department)
Engineering College – Baghdad University
Email:[email protected]
Assistant professor
Engineering College – Baghdad University
Email: [email protected]
ABSTRACT
This study produces an image of theoretical and experimental case of high loading stumbling
condition for hip prosthesis. Model had been studied namely Charnley. This model was modeled
with finite element method by using ANSYS software, the effect of changing the design
parameters (head diameter, neck length, neck ratio, stem length) on Charnley design, for
stumbling case as impact load where the load reach to (8.7* body weight) for impact duration of
0.005sec.An experimental rig had been constructed to test the hip model, this rig consist of a
wood box with a smooth sliding shaft where a load of 1 pound is dropped from three heights.
The strain produced by this impact is measured by using rosette strain gauge connected to
Wheatstone bridge for the model .The signal is amplified and sent forward to a data acquisition
and then saved in the connected laptop. From this study it is found that the changing in stem
length had large effect on effective stress where the change in effective stress while stem length
increased from (110mm to 140mm) was not more than (209MPa).
Keywords: hip prosthesis; charnley design; finite element method; design parameters; data
acquisition
‫تأثير الحمل الذيناميكي على االجهادات المتىلذة في مفصل الىرك الصناعي من نىع جارلي‬
‫محمىد وائل سعيذ‬
)‫طاىب ٍاصغخٍش ( قغٌ اىٍَناٍّل‬
‫ميٍت اىْٖذعت – صاٍعت بغذاد‬
‫أحمذ عبذالحسين علي‬
‫اعخار ٍغاعذ‬
‫ميٍت اىْٖذعت – صاٍعت بغذاد‬
‫الخالصه‬
ٌ‫ٕزٓ اىذساعٔ قذٍج حص٘س ّظشي ٗعَيً عِ حاىٔ حَو عاىٍٔ صذا ًٕ حاىت اىخعزشعيى بذٌو ٍفصو اى٘سك اىصْاعً ٗقذ ح‬
ٔ‫حٌ حَزٍو اىَْ٘رس بطشٌقٔ اىعْاصش اىَحذدٓ ٗرىل ب٘اعطت بشّاٍش االّغض ىيَ٘دٌو صاسىً ٗدساع‬.ً‫دساعت ٍ٘دٌو ٍِ ّ٘ع صاسى‬
‫ ط٘ه اىضزع) ىحاىت‬, ‫ ّغبت حغٍٍش اىعْق‬, ‫ ط٘ه اىعْق‬, ٓ‫حأرٍش حغٍٍش اىَخغٍشاث اىخصٍٍََٔ ىيَ٘دٌو صاسىً (ّصف قطش اىنش‬
ٍٔ‫اىطشٌقت اىعَي‬.ٍّٔ‫ ٍييً را‬1 ‫* ٗصُ اىضغٌ) ٗىَذة صذٍٔ ٍقذاسٕا‬7.8 ( ‫اىحَو اىصذًٍ فً حاىت اىخعزش حٍذ ٌصو اىحَو اىى‬
‫ٗحٌ ححغظ‬. ‫اىخً حٌ اىعَو بٖا ًٕ صْاعت ٍٕنو ٍغخطٍو ٍض٘ف بذاخئ رساع اٍيظ ٌْضىق عئٍ اىحَو ٍِ رالد اسحفاعاث‬
ٔ‫االّفعاه اىْاحش ٍِ اىصذٍٔ ب٘اعطت ٍقٍاط اّفعاه رالرً ىيَ٘دٌو صاسىً حٍذ حٌ اعخخذاً قْطشة ٗحغخِ ٍٗضخٌ ف٘ىخٍٔ ىخخض‬
‫ٗصذ اُ امزش اىَخغٍشاث اىخصٍٍََٔ حأرٍشا عيى االصٖاد اىَحصو‬.‫االشاسٓ ّح٘صٖاص حٍاصة اىبٍاّاث ٍٗح٘ىٖا رٌ اىى اىنٍ٘بٍ٘حش‬
ٍِ ‫فً اىضضء االضعف فً ٍ٘دٌو صاسىً ٕ٘ ط٘ه اىضزع حٍذ اُ ٍقذاس اىخغٍش فً االصٖاد االعظٌ عْذ حغٍٍش ط٘ه اىبذٌو‬
.)‫ ٍٍضاباعناه‬912( ‫ٍيٌ) ىٌ ٌخضاٗص‬141 ‫ٍيٌ اىى‬111(
‫ صٖاصحٍاصة‬،‫ اىَخغٍشاث اىخصٍٍََت‬،ٓ‫ طشٌقت اىعْاصش اىَحذد‬,ً‫ حصٌٍَ صاسى‬,ً‫ ٍفصو اى٘سك اىصْاع‬:‫الكلمات الرئيسيه‬
.‫اىبٍاّاث‬
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Journal of Engineering
1. INTRODUCTION
This work presents an overview about the hip joint, the causes of its failure and the historical
attempts to overcome this problem as well as the most important stem types used in this field
enhanced by some definitions and concepts related to the shape variables and materials. Total
hip replacement is most commonly used to treat joint failure caused by osteoarthritis or other
diseases. The aims of the procedure are pain relief and improvement in hip function. Hip
replacement is usually considered only once other therapies, such as physical therapy and pain
medications, have failed. In order to design a successful stem implant some important things
must take in account such human activities, weight and age. Some of researchers such as ,H.F.
El’Sheikh, et.al., 2003, studied a component (hip prosthesis) had been subjected to a dynamic
load due to stumbling and the peak static load of the same patient load activity. Two quantitative
measures are calculated: peak stress and stressed volume. It has been shown that each measure
may lead to differing conclusions. It is concluded that from a thorough analysis of the hip
prosthesis components (prosthesis, cement mantle and bone) it is not the peak stress but rather
the proportion of the stressed elements (or stressed volume) which should be the indicator if a
precise analysis of the load transfer mechanism is required. In static analysis the material was
assumed to be linear elastic continuum with isotropic properties, whereas in dynamic analysis it
was assumed to be bi-linear elastoplastic, and studied the effect of some design parameter such
as stem thickness, the effect of changing the material, the effect of changing the stem length, the
effect of collar of hip prosthesis and the effect of damper on stresses induced in prosthesis.
2. FINITE ELEMENT MODEL
The concept of piecewise discretization or dividing a complex object into simpler pieces is one
of the oldest logical concepts known to man, when trying either to construct a complex shape or
to understand an enigmatic phenomenon. More recently, structural engineers had developed
matrix methods for the analysis of framed structures, which can easily be recognized as
assemblages of members or, element, connected by joints, or nodes. The finite element (FEM)
can now be considered as the most popular theoretical technique ever known to man, and it has
been applied successfully to many engineering disciplines, such as structural mechanics,
computational fluid dynamics, tribology, heat transfer , electromagnetism, biomechanics,… etc.
The Charnley model which was used should be discretized to small elements for finite element
analysis; the element type that used in this discrediting was SOLID45, 10-node tetrahedral.
SOLID 45 has a quadratic displacement behavior and is well suited to modeling irregular
meshes; the element is defined by 10 nodes having three degrees of freedom at each node:
translations in the nodal x, y, and z directions as shown in Fig. 1 , the element has plasticity, ,
creep, stress stiffening, large deflection, and large strain capabilities with respect to contact
region between cup and femoral head the element contact 174 had been used where this is a
three- dimensional, eight-node , higher order quadrilateral element that can be located on the
surfaces of three- dimensional solid or shell element with mid side nodes, It can be degenerated
to 3-7 node quadrilateral triangular shapes, and also element target where it is a threedimensional element and shape is described by a sequence of triangles, quadrilaterals, straight
lines , parabolas, cylinders, cones, (Release 14.0 Documentation for ANSYS 2012).With
changing the coarser of this element in order to investigate the right element number. The result
of the convergence test show that the best element number that can 253481elements as in
Fig. 2 .
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3. MATERIAL PROPERTIES
The material properties of each types of hip prosthesis that are used in present work are
illustrated in Table1, Zafer Senalp , et.al., 2007, below where the Charnley hip prosthesis is
made from (stainless steel alloy 316L)..And acetabulum cup made from ultra-high molecular
weight polyethylene (UHMWPE), Mamdouh, 2012.
4. LOADING AND BOUNDARY CONDITION
For dynamic analysis, the load time curve during walking that applied as time history of the
dynamic load components for 5 s show that the maximum load applied on hip prosthesis reached
to 8.7 times the body weight during stumbling case so the case with this excessive load should
be studied, In our study we take stumbling case as impact load with time of impact (impact
duration) of (0.005sec), El’Sheikh, et.al., 2003,. The boundary condition which had been
applied in this work is according to (ISO-7206 standard, modified in 2002) .Where 60% of stem
length (which is the distance from stem distal point to center of head ball) was fixed, Chantsungyang, et. al., 2009. The design parameters that studied is shown in the Fig. 3 Charnley
model.
5. EXPERIMENTAL
5.1 Model to be Tested
In this study real models of total hip prosthesis which had been bought it from market deal with
prosthesis ( DePuy-Synthes device market).We used Charnly hip prosthesis for this type of total
.The dimensions of Charnley hip prosthesis is shown in Table 2. . Fig. 4 shows the real
Charnley model that had been studied.
5.2 Experimental Circuit
The interface circuit which has been used consists of rosette strain gage and whetstone bridge
with signal amplifier and this circuit is connected to data acquisition of 16 Flexible I/O (Digital
Input, Digital Output, or Analog Input) (LabJack–U3-LV,Colorado,USA) and it is able to read
and write the signal in millisecond . This system was linked to a computer for storage and
analysis of data using software LabJack UDV3.25computer to record the results with time, the
circuit is shown in Fig. 5.Where this figure showed the method of circuit connections and its
parts.
5.3 Testing Device
The test rig has been designed to simulate the environments of loading case of reference,
Farhad N. et. al., 2008, where a frame work consists of smooth steel sliding shaft that allows
weights to be dropped on the hip prosthesis from different height up to 30 cm ,as shown in Fig.
6 which shows the test rig and the assisting measuring devices . In the different impact loads
had been applied by falling weight of (1pound=453.59g) from 30cm then from 20cm and then
from 10cm. A rosette strain gauge (Tokoyo Sokki Kenkyujo co.,LTD. –Japan) attached on the
hip prosthesis (Charnley) connected to a Wheatstone bridge with signal amplifier measures the
strain and gives the amplified signal from(0 to 4.8 volt) to LabJack data acquisition where a
stream UD software gives the final values of strain with the aid of scaled equation of voltage.
The final results are compared with those obtained by ANSYS. One of the most important case
in experimental part is the fixation of the model during the test because the bad fixation may
lead to wrong results and also became a far from reality, the (ISO7206-4 standard, Modified in
2002) solved this problem where by this standard we can become near to the reality case. In this
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study according to modified ISO7206-4 standard 60% of stem length of hip prosthesis is fixed
by using gypsum type 4(elite stone ,thixotropic,zermak-italy) which is used for fixation of
master models in removable prosthesis. The fixing stone holds the distal end of the stem starting
at 40% from center of the femoral head with stone thickness of 70mm.In addition, the stem is
aligned at 10◦ in adduction and 9◦ in flexion, Chan-tsungyang, et. al.2009, as shown in Fig.7
showed the fixation of Charnley type Tables 4, 5 shows comparison between numerical and
experimental results
6. RESULTS
In Figs. 8, 9 different head and diameter (22mm,26mm) respectively were shown and it is clear
from this figure that the position of maximum effective stress for both sizes was the same ,
where increasing head diameter lead to increase maximum effective stress by (16%), this is due
to the shifting of load position which increases the moment on the weakest part. The effective
stress for Charnley design with (a) 32mm neck length and (b) 40mm neck length, shown in Fig.
10,11. certainly increasing neck length will lead to increase maximum effective stress and that is
clear from this figure. Increasing neck length from 32mm to 40mm lead to increase the
maximum effective stress by (1.5%) it is small value compared with increasing head diameter or
increasing stem length. It should be noted that increasing neck length lead to increase the
effective stress at necking section by (32%). The effect of varying two neck ratio ((a) 0.5, (b)
0.8) is shown in Figs. 12, 13, respectively, it's clear to be noted that increasing neck ratio is not
effected with large amount on maximum effective stress where increasing neck ratio from (0.5
to 0.8) didn't change the maximum effective stress at stem more than (3%), but decreases the
effective stress at neck by (28%), this is due to reduction in stress concentration at necking
section.
Figs. 14, 15. show the effective stress for Charnley design with stem length (a) 110mm (b) 140
mm, from figure the maximum effective stress is at the same position for both stem sizes with
different values where maximum effective stress increased by (16%) with increasing stem
length. This is due to the reduction in cross sectional area of the loaded section with increasing
stem length.
7. DISCUSSION
Fig. 16 shows the variation of effective stress with respect to changing the head diameter , the
relation theme gives indication that with increasing the head diameter the effective stress in
weaken part of hip prosthesis will increase and this relation may be caused by the sweeping of
load position in vertical direction due to increase the head diameter, this sweeping of load
position lead to increase moment at weaken part and thus will increase the stress. The change in
effective stress values while head diameter increased from(20mm to 26mm) with step of 2mm
was not more than (73Mpa) except head diameter of 22mm where change in effective stress
reached to (121Mpa).
Fig. 17 shows the variation of effective stress with changing of neck ratio(neck ratio: represent
the position of necking part with respect to total neck length),the chart theme shows that it
should take into account while designing to make the neck ratio more than 0.5 as possible to
decrease the force arm on neck where this may prevent the fracture at neck and lead to decrease
the stress at weaken region of hip prosthesis so it should take into consideration to make
balancing of changing this factor and it is clear that changing of stress is not more than (42Mpa)
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for changing this parameter from (0.5 to 0.8).Except neck ratio of (0.6) where change in
effective stress reached to (97MPa).
Fig. 18 shows the variation of effective stress with respect to changing the third design
parameter that is the stem length and so due to this point it is clear to most biomedical
researchers and (Depuy-synthes) manufacturing companies, that produced medical orthotropic
products, to reduce the stem length as possible to prevent the increasing in stress where this
increasing in stress may be caused by three reasons the first one is by increasing stem length the
overall mass of system with axial axis of hip prosthesis will increase, the second reason is
increasing the stem length lead to increase the free part of the fixed hip prosthesis according to
(ISO_7204 standard modified in 2002) and that lead to increase the bending stress in weaken
part. Second thing is increasing the weight of free part of fixed hip prosthesis. The third reason
is increasing stem length lead to decrease the stem cross sectional area to be loaded; this
decreasing in stem cross sectional area is due to curvature shape of stem. The change in effective
stress while stem length increased from (110mm to 140mm) was not more than (209Mpa)
except stem length of (130mm) where change of effective stress reached to nearly (245Mpa)so
the stem length of (130mm) and what is nearest to this value should be averted while designing
stem.
Fig. 19 shows the variation of effective stress in weaken part of hip prosthesis (at stem) with
changing the neck length and it is clear that increasing neck length lead to increase the effective
stress due to increase the arm of force where that leads to increase the stress. In this study five
sizes of neck length had been used, and it turned out that changing of neck length from(110mm
to 140mm) lead to change the effective stress with value more than (53Mpa) except neck length
of (36mm),(32mm) where change jumped to (73Mpa).
8. CONCLUSIONS
1. It is found that changing in stem length lead to increase the effective stress with values
higher than the other designs parameters so it should be taken in account this parameter
because of its heavy influence on effective stress so for Charnley design the stem length
should be decreased as possible, under cases of impact load. Changing in effective stress
not exceeded (22%).
2. It is found that the changing in head diameter had an influence on effective stress values
but with small amount as compared with stem length, where changing in effective stress
not exceeded (16%).
3. It is found that the increasing of the neck length for Charnley design lead to increases
effective stress with values less than stem length where changing in effective stress not
exceeded (5.5%). So that it must be decreased as possible, where increasing neck length
lead to increase maximum effective stress.
4. The effect of the ball radius on both contact pressure and total contact stress is larger than
that on the effective stress. Where changing in contact pressure not exceeded (41%), and
changing in total contact stress not exceeded (32%).
5. It is found that increasing the neck ratio had an effect on the effective stress, where
changing in effective stress not exceeded (7%).
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6. It is found that the best sizes of low effective stress with these dimensions (head diameter
of 22mm, 0.6 neck ratio, stem length of 110mm, neck length of 24mm) can be considered
as safest sizes.
REFERENCES

A. Zafer Senalp , Oguz Kayabasi, Hasan Kurtaran, 2007, Static and Dynamic and
Fatigue Behavior of Newly Designed Stem Shapes for Hip Prosthesis Using Finite
Element Analysis, Materials and Design, vol.28, No.4 pp. 1577–1583.

Chan-tsungyang, hung-wen wei,hung-and chankao,cheng-kung cheng, 2009, Design and
Test of Hip Stem or Medullary Revascularization, Medical Engineering and Physics,
vol.21, No.3 ,pp.994-1001.

H.F. El’Sheikh, B.J. MacDonald, M.S.J. Hashmi, 2003, Finite Element Simulation of The
Hip Joint During Stumbling: a Comparison Between Static and Dynamic Loading,
Journal of Materials Processing Technology vol.144, No. 2, pp. 249–255.

Mamdouh M. Monif, 2012, Finite Element Study on The Predicted Equivalent Stresses
in The Artificial Hip Joint , IVSL/ J. Biomedical Science and Engineering, vol.5, No.2,
pp.43-51.

Release 14.0 Documentation for ANSYS, Elements Reference, Part I, Element Library.
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Figure 1. Solid45 geometry.
Figure 2. Convergence test.
Figure 3. Design parameters and boundary condition, Charnley.
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Figure 4. Charmly hip prosthesis, upper view of white acetabulum part (cup),
femoral part(stem).
Figure 5. Interface circuit .
Figure 7. Structure of testing
device.
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Figure 7. Fixation of hip prosthesis according to ISO7206 standard where: a- fixation of Charnley hip
prosthesis.
Figure 8. Charnley model effective stress 22mm head
diameter.
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Figure 9. Charnley model effective stress 26mm head
diameter.
Figure 10. Charnley model effective stress 32 mm neck
.lengths.
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Figure 11. Charnley model effective stress 40 mm neck length.
Figure 12. Charnley model effective stress 0.5 neck ratio.
Figure 13. Charnley model effective stress 0.8 neck ratio.
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Figure 14. Charnley model effective stress 110 stem length.
Figure 15. Charnley model effective stress 140 stem length.
Figure 16. Variation of effective stress of Charnley model with changing head
diameter.
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Figure 17. Variation of effective stress of Charnley model with changing neck
ratio.
Figure 18. Variation of effective stress of Charnley model with changing stem length.
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Figure 19. Variation of effective stress of Charnley model with changing neck length.
Table 1. Material properties.
Material
Young's Modulus (GPa) Poisson's Ratio (v) Density (g/ cm^3)
Stainless steel
193
0.32
8
UHMWPE
1.2
0.4
0.945
Table 2. Dimensions of Charnley model.
Head Diameter (mm) Neck Length (mm) Neck Ratio (mm) Stem Length (mm)
20
24
0.5
110
22
29
0.6
120
24
32
0.7
125
25
34
0.75
130
26
40
0.8
140
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Table 3. Comparison between experimental and numerical results for Charnley design .
Experimental Effective
Stress(MPa)
Error Percent
(%)
10
ANSYS
Effective Stress
(MPa)
12.15
11.056
9
20
17.183
15.842
7.8
30
21.8131
20.046
8.1
Height of Load
Dropping (cm)
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Structural Behavior of Reinforced Concrete Hollow Beams under Partial
Uniformly Distributed Load
Ahmad Jabbar Hussain Alshimmeri
Instructor
Engineering College - Baghdad University
E-mail: [email protected]
Hadi Nasir Ghadhban Al-Maliki
Instructor
Engineering College - Mustansiriya University
E-mail: [email protected]
ABSTRACT
A
Longitudinal opening is used to construct hollow core beam is a cast in site or
precast or pre stressed concrete member with continuous voids provided to reduce weight, cost and,
as a side benefit, to use for concealed electrical or mechanical runs. Primarily is used as floor beams
or roof deck systems. This study investigate the behavior of six beams (solid or with opening) of
dimension (length 1000 x height 180 x width120mm) simply support under partial uniformly
distributed load, four of these beam contain long opening of varied section (40x40mm) or
(80x40mm). The effect of vertical steel reinforcing, opening size and orientations are investigated to
evaluate the response of beams. The experimental behavior based on load-deflection measured at
central and quarter of tension zones. The experimental test result shows the presence of Hollow
decrease the load carrying capacity by about (37.14% to 58.33%) and increased the deflections by
about (71.6% for (Hollow ratio 7.4%) to 75.5% for (Hollow ratio 14.8%)) for same applied load
compared with solid beams with the same properties. The increase shear steel reinforcing will
decrease all the deformations at all stages of loading, but particularly after initial cracking and give
enhancement in ultimate load capacity of beams by about 31.5% with increasing the amount of
shear steel reinforcing by about 50%. Finally, ductility is increased in all cases under partial
uniformly distributed load when hollow ratio decreased by about 50% or increased in shear steel
reinforcing by about 50%.
Key words: longitudinal opening, shear reinforcing, first crack, deflection, hollow ratio.
‫السلوك اإلوشائي للعحبات الخرساوية المسلحة المجوفة جحث حمل موزع باوحظام جسئيا‬
‫هادي واصر غضبان المالكي‬
‫ٍذسط‬
‫ اىجاٍؼت اىَغخْصشَت‬- ‫ميُت اىهْذعت‬
‫احمذ جبار حسيه الشمري‬
‫ٍذسط‬
‫ جاٍؼت بغذاد‬- ‫ميُت اىهْذعت‬
‫الخالصة‬
ٍّ‫اىفخحاث اىطىىُت حغخؼَو ىخنىَِ ػخبت ٍجىفت ٍصبىبت ٍىقؼُا" أو ٍغبقت اىصب أو ٍغبقت اإلجهاد وٍغخَشة اىفشاغاث ٍغ اىؼضى اىخشعا‬
‫ االعخؼَاه اىشئُغٍ هى مؼخباث اىطىابق او‬. ‫ورىل ىخخفُف اىىصُ ومزىل اىنيفت واىفائذة اىشئُغُت هى ىخَشَش اىخذٍاث اىنهشبائُت واىَُناُّنُت‬
ٌ‫ٍي‬081 ‫ ٍيٌ واالسحفاع‬0111 ‫ هزٓ اىذساعت ححشث عيىك عج ػخباث خشعاُّت ٍغيحت ( صيذة او ٍجىفت ) وبأبؼاد ( اىطىه‬.‫أّظَت اىغقىف‬
‫ ٍيٌ او‬01*01( ‫ أسبؼت ٍِ اىَْارج ٍجىفت وبأبؼاد حجىَف ٍخخيفت‬،ً‫ ٍيٌ ) بغُطت اإلعْاد ححج حأثُش اىحَو اىجضئٍ اىَىصع باّخظا‬021 ‫وػشض‬
‫ حٌ دساعت حأثُش ّغبت اىخغيُح اىؼَىدٌ وّغبت اىفخحت واحجاهها ىخقٌُُ اعخجابت اىؼخباث ٍِ اىْاحُت اىؼَيُت باالػخَاد ػيً ػالقت‬.)ٌ‫ ٍي‬81*01
‫ ّخائج اىفحص اىؼَيٍ بُْج اُ وجىد اىخجاوَف (اىفخحاث اىطىىُت) فٍ اىؼخباث‬.‫ اىحَو اىَقاط فٍ ٍشمض وسبغ اىطىه ححج ٍْطقت اىشذ‬- ‫اىهطىه‬
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‫ ىْغبت حجىَف‬%13.3 ً‫ اى‬%10.7( ‫ ) وحضَذ فٍ اىهطىه بَقذاس‬%38.44 ً‫ إى‬%41.00 ( ٍ‫اىخشعاُّت حقيو قابيُت اىخحَو ىها بَقذاس حىاى‬
‫ مزىل صَادة حذَذ اىقص‬,‫ػيً اىخىاىٍ) ىْفظ اىحَو اىَغيط وباىَقاسّت ٍغ اىؼخباث اىصيذة وىْفظ اىخصائص األخشي‬%00.8 ‫ و‬%1.0 ‫ٍقذاسها‬
‫ ٍغ صَادة‬%40.3 ‫َقيو مو اىخشىهاث فٍ مو ٍشاحو اىخحَُو وىنِ ػَيُا بؼذ اىخشقق األوىٍ وحؼطٍ ححغُِ فٍ قابيُت اىخحَو ىيؼخباث بَقذاس‬
%31 ‫ أخُشا" اىَطاوػت حضداد فٍ مو اىحاالث ححج حأثُش اىحَو اىَىصع باّخظاً ػْذ ّقصاُ ّغبت اىخجىَف بَقذاس‬.%31 ‫حذَذ اىقص بَقذاس‬
.% 31 ‫أو صَادة حذَذ اىقص بَقذاس‬
1. INTRODUCTION
Many parameters may influence the overall hollow girder response such as: the shape of the
section, the amount of the longitudinal and transverse reinforcement, the cross section thickness,
load ratio and finally the material strength of concrete and reinforcement, Alnuaimi, 2003 and
Mander, 1984. This study focuses on rectangular hollow cross sections and investigates the beams
behavior under a state of uniformly distributed loading
2. ADVANTAGE OF HOLLOW CROSS SECTION
The advantages of hollow cross section , Nimnim, 1993.
1. Reduced the weight, which affects especially the cost of transport, handling and erection for precast cross sections.
2. Substantial reduction of material quantities, the materials required are usually much less than
those needed for other conventional systems and they are little more than those required for
continuously curved shells, with the advantage of utilizing relatively simple formwork.
3. OBJECTIVE OF THE RESEARCH
The main target of this research is studying the effect of different amount of shear
reinforcement (stirrup) and hollow ratio of cross section on the strength and behavior of hollow
cross section beams subject to partial distributed load and also studying load deflection behavior
which occurs at the center and quarter of span length of beams.
The variables which taken in this research are: stirrups (shear reinforcement, hollow and solid
section with thickness of walls for hollow section.
It’s expected in this research to state the influence of distributed load on the strength and behavior
of hollow cross section beam and comparison between experimental tests result of specimens and
confirm the best specimens with hollow section which result the nearest value to the solid section
result.
Finally studying the factors that affect the behavior of reinforced concrete beams under
partial uniformly distributed load which have directly relation with the (stirrup reinforcement and
dimension of sections).
4. EXPERIMENTAL WORK
4.1 Scope of Work
In order to study the structural behavior and ultimate strength of reinforced concrete beam
under partial uniformly distributed load, which can be used as rectangular hollow cross section. A
total of six specimens in four groups, detailed as shown in Table 1, were cast in plywood forms.
All the beams were made from a single mix proportion (Cement: Sand: Gravel) of 1:1.5:3 by
weight with a water/cement ratio 0.45 and also all beams were designed to have the same
longitudinal and varied stirrup reinforcing. Each of the mixtures was thoroughly mixed prior to
casting. The beams details, mix proportion, materials properties and formwork given in Tables 1,
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2, 3 and 4, and Figs. 1,2 and 3 respectively.
4.2 Considered Parameters
In the present investigation, four group parameters were adopted to study the behavior and
ultimate load of beams and to investigate the influence of hollow ratio, shear reinforcing in
concrete beams when subjected to uniformly distributed load. All beam details are shown in Table
1.
Group 1: Consists of one solid specimen with dimension (120, 180) mm, length (1000 mm),
longitudinal bars (3-Ø12mm) with stirrups of (Ø10mm @ 100 mm c/c).
Group 2: Consists of one solid specimen with dimension (120, 180) mm, length (1000 mm),
longitudinal bars ( 3Ø10 mm) with stirrups of (Ø10 mm @ 50 mm c/c).
Group 3: Consists of two hollow specimens, all properties as same in group 1, but with different
hollow section (40x40 mm and 40x80 mm). Group 4: Consists of two hollow specimens, all
properties as same in group 2, but with different hollow section (40x40 mm and 40x80 mm).
5. TEST RESULTS OF REINFORCED CONCRETE BEAMS
A partial uniformly distributed load (i.e. loaded length 120mm which equal to 13.34% of
span length) was provided using universal testing machine of capacity (3000 kN) applied at the
center of the beam gradually at increments of (5 kN) up to failure. Test results for each case,
including deflections and cracking are highlighted. Load versus deflection was recorded at point of
(central and quarter of span length ) at distances about (500 and 250 mm) from the edges of the
beam. Arrangement specimens of partial uniformly distributed loading and instrumentation as
shown in Figs. 4 and 5. Crack patterns, first crack load and propagation of cracks are also studied.
Ultimate load capacity and failure modes are recorded as shown in Table 5. A study of the effect of
vertical shear reinforcement and section type (solid or hollow), was carried out. Deflections, crack
patterns at all stages of loading of the reinforced concrete beam were also discussed.
6. CRACK PATTERNS
The first crack was found to develop around the sides of the loading area of (120mm 2) on
the tension fiber of the beam center. These cracks were formed at about (8.0 ‫ ــ‬11.5%) of the
ultimate failure load, as shown in Table 5. In the case of beams with hollow section cracks appear
in the tension zone of the beam near one or more of the corners as shown in Table 5. The ultimate
load, maximum central deflection were recorded and given in Table 5. As the load is increased
after formation of the first crack, more cracks begin to appear and, propagated diagonally towards
the corners of applied load (i.e. under position of applied load). At high loads, these cracks
extended with the formation of new cracks at different orientations. Meanwhile, cracks start to
appear around the edge of the applied load at tension zone.
Failure was distinguished by the successive deflections at the center of the beam at higher
load levels through shear and wide flexural cracks at the tension zone, then, yielding of the tensile
reinforcing steel. All beams were tested up to failure. The crack pattern zone of each reinforced
concrete beam was painted with concrete color this allows the cracks to be visible and the failure
can be pointed as shown in Figs. 6 to 11.
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7. DEFLECTION MEASUREMENT
For all tested beams, deflections were measured at a distance of (500mm and 250 mm) from
the ends of beams at the bottom surface. The deflections occur at these locations were measured to
compare response.
Deflection measures may give a reasonable interpretation of the load carrying capacity of the
beams. The load-deflection curves for six tested beams under applied loads are shown in Figs. 12
to 16, While the comparison of deflection for all beams at quarter and central location as show in
Figs. 17 and 18 for the cases of beam solid or hollow section. While, these curves demonstrate a
certain tendency in which, at early stages of loading (elastic stage), the deflection-load relation is
linear up to the first cracking load. After this, new cracking start and continuous up to the first
yielding; these are flexural cracking. Beyond first yielding plastic deformations continuous and
yielding up to failure at a stress near the ultimate flexural strength, as calculated by the yield line
theory. In this stage, yielding of the tension reinforcement spreads from the loaded area towards the
beam edges. Finally (stage of failure) a plastic stage of rapidly increasing deflection at no
additional load application.
Tests of all beams demonstrated that the ultimate load becomes smaller as the beam varied from
solid to Hollow by about (37.14% to 58.33%). Also ultimate load increases as shear reinforcement
ratio increases. The deflections of the beams at both points (A and B) increase when the beam
varied from solid to hollow section (71.6% (hollow ratio of 7.4%) to 75.5% (hollow ratio of
14.8%)) for the same applied load compared with solid beams with the same properties and noticed
smaller values when increased shear reinforcing as shown in Table 5. In general R.C. beams those
are solid or hollow with more shear reinforcing show higher load carrying capacity with reduction
in deflection values. Finally the deflection varied along of all tested specimens at loading stages are
shown in Figs. 19 to 24.
8. CONCLUSION
In this study it has become to study the behavior and strength of hollow concrete beams
under partial uniformly distributed load was investigated. From an experimental program the
following conclusion were drawn:
1- It has been observed from the tests carried out that the slope of main cracks under partial
uniformly distributed load for reinforced concrete beam is about 45o.
2- As per the result of tested, some of concrete beams fails under flexural failure and other
compound failure (i.e. shear and flexural failures) when the crack constructed at flexural zone or
flexural and near support under load.
3- The presence of hollow recess in reinforced concrete beams was found to decrease the load
carrying capacity by about (37.14% to 58.33%) and increase the deflections by about (71.6%
(hollow ratio 7.4%) to 75.5% hollow ratio (14.8%)) for same applied load compared with solid
beams for same properties.
4- When increasing the hollow ratio from (7.4% to 14.8%) the load carrying capacity is decreased
and deflection is increased by about (28.5% and 14%) respectively for same other properties.
5- Shear steel reinforcement decreased all the deformations at all stages of loading, particularly after
initial cracking.
6- Ductility is increased in all cases for partial uniformly distributed load when decreased Hollow
ratio by about 50% or increased in steel reinforcing.
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7- The phenomenon of crushing concrete cover (Spalling down) was avoided when increased the
shear steel reinforcing by about 50% in the reinforced concrete beam under partial uniformly
distributed load.
9. REFERENCES
Abbas, N. J., 2000 , Structural Behavior of Ferrocement Box-Beam, Deploma, Research, University
of Technology.
ACI 318M – 11, 2011, Building Code Requirements for Reinforced Concrete, ACI Committee
318M.
Alnuaimi, A.S., 2003, Parametric Study on the Computational Behaviour of Hollow Beams
Designed Using the Direct Design Method - Numerical Factors, Proceedings of International
Conference on Advances in Structures, ASSCCA'03, Sydney, Australia, A.A., 22-25 June, Balkema
Publishers, Vol. 2, pp. 1017 - 1021.
Alnuaimi, A.S., 2002, Parametric Study on the Computational Behaviour of Hollow Beams
Designed Using the Direct Design Method - Material Factors, Proceedings of High Performance
Structures and Composites, Seville, Spain, WIT Press Publishers, March, pp. 605-614.
British Standard Institution (BS 8110), 1997, Code of Practice for Design and Construction, British
Standard Institution Part 1, London.
Mander J.B. ,1984, Experimental Behavior of Ductile Hollow Reinforced Columns, In Proceedings,
8th World Conference on Earthquake Engineering, Vol. 6, pp. 529-536.
Nilson, A. H. , Darwin, D. and Dolan, C. W., 2006, Design of Concrete Structure McGraw-Hill
Book Company.
Nimnim, H. T., 1993, Structural Behavior of Ferrocement Box-Beams, M.Sc., thesis, University of
Technology.
Oehlers, D. J., and Bradford, M. A., 1995, Composite Steel and Concrete Structural Members,
Kidlington, Oxford, U.K.: Elsevier Science, Ltd.
Takahashi Y., Iemura H., 2000 Inelastic Seismic Performance of RC Tall Piers with Hollow Section,
In Proceedings, 12th World Conference on Earthquake Engineering, ref. 1353.
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Table 1. Details of reinforced concrete beams specimens.
Specimen
Symbol
B1
Bottom
Reinforcing
3 Ø 12 mm
Top
Stirrups
Reinforcing Reinforcing
2 Ø 12 mm Ø[email protected] mm
B2
3 Ø 12 mm
2 Ø 12 mm
B3
3 Ø 12 mm
B4
Hollow Ratio
---
Section
Property
Solid
Ø[email protected] 50 mm
---
Solid
2 Ø 12 mm
Ø[email protected] mm
7.4%
Hollow
3 Ø 12 mm
2 Ø 12 mm
Ø[email protected] 50 mm
7.4%
Hollow
B5
3 Ø 12 mm
2 Ø 12 mm
Ø[email protected] 50 mm
14.8%
Hollow
B6
3 Ø 12 mm
2 Ø 12 mm
Ø[email protected] mm
14.8%
Hollow
Table 2. Mix proportions for (1 m3) of concrete (1: 1.5: 3) by weight.
Cement
(kg/m3)
400
Sand
(kg/m3)
590
Gravel Water/Cement Water
(kg/m3)
Ratio
(kg/m3)
1180
0.45
180
Table 3. Properties of steel reinforcement.
Nominal
Diameter
(mm)
10
Measured
Diameter
(mm)
9.88
As
(mm2)
Yield Stress fy
(MPa)
76.67
421
Tensile
Strength fu
(MPa)
520
12
12.2
116.89
480
570
Table 4. Compressive strength of concrete cylinder (150 x 300 mm) (28 days).
Sample No.
1
Strength
(MPa)
29.43
2
28.41
3
27.73
135
Average Strength
(MPa)
28.52
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Figure 1. Moulds of reinforced concrete solid and hollow reinforced concrete beams.
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Figure 2. Cross-section & longitudinal shape of the beam.
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Figure 3. Recess through section of
hollow beams.
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Figure 4. Beams under partial uniformly distributed loading.
Figure 5. Arrangement specimens of partial uniformly distributed loading and instrumentation.
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Table 5. First crack, ultimate load and deflections.
Beam Beam
No. Section
Shear
Reinforcing
Hollow
Ratio
%
Ultimate
Load
(Wu)
kN/m
Central
Deflection
( mm )
Wcr /
Wu
%
60.0
3.32
8.3
B1
Solid
Ø[email protected] mm
---
First Crack
Load
(Wcr)
(kN/m)
5.0
B2
Solid
Ø[email protected] mm
---
10.0
87.5
3.72
11.5
B3
Hollow
Ø[email protected] mm
7.4
4.0
40.0
5.70
10.0
B4
Hollow
Ø[email protected] mm
7.4
5.0
55.0
8.08
9.0
B5
Hollow
Ø[email protected] mm
14.8
3.0
35.0
5.69
8.5
B6
Hollow
Ø[email protected] mm
14.8
2.5
27.0
4.3
9.2
Figure 6. Crack patterns of beam (Solid) B1.
Figure 7. Crack patterns of beam (Solid) B2.
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Figure 8. Crack patterns of beam (Hollow) B3.
Figure 9. Crack patterns of beam (Hollow) B4.
Figure 10. Crack patterns of beam (Hollow) B5.
Figure 11. Crack patterns of beam (Hollow) B6.
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60
80
50
70
40
50
Load, kN
Load, kN
60
40
30
30
20
20
10
10
0
0
0
0.5
1
1.5
2
2.5
3
3.5
4
0
1
2
3
Deflection, mm
B1,Stirrups Ø10 @100, Solid
4
5
6
7
8
9
Deflection, mm
B3 ,Stirrups Ø10 @100 Hallow ratio 7.4%
B2 ,Stirrups Ø10 @50 Solid
Figure 12. Comparison of central
deflection of beams B1 & B2.
B4 ,Stirrups Ø10 @50 Hallow ratio 7.4%
Figure 13. Comparison of central
deflection of beams B3 & B4.
60
40
35
50
30
40
Load, kN
Load, kN
25
20
15
30
20
10
10
5
0
0
0
1
2
3
4
5
0
6
B5,Stirrups Ø10 @50, Hallow ratio 14.8%
1
2
3
4
5
6
7
8
9
Deflection, mm
Deflection, mm
B4 ,Strriup Ø10 @50 ,Hallow ratio7.4%
B6, StirrupsØ10 @100, Hallow ratio 14.8%
Figure 14. Comparison of central
deflection of beams B5 & B6.
B5 ,Stirrups Ø10 @50 ,Hallow ratio 14.8%
Figure 15. Comparison of Central
Deflection of Beams B4 & B5.
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40
35
30
Load, kN
25
20
15
10
5
0
0
1
2
3
4
5
6
Deflection, mm
B6,Stirrups Ø10 @100,Hallow ratio 14.8%
B3,Stirrups Ø10 @100, Hallow ratio7.4%
90
90
80
80
70
70
60
60
Load, kN
Load, kN
Figure 16. Comparison of central
deflection of beams B6 & B3.
50
40
50
40
30
30
20
20
10
10
0
0
0
1
2
3
4
5
6
7
0
Deflection, mm
B1,Stirrups Ø10 @100, Solid
B3,Stirrups Ø10 @100, Hallow ratio 7.4%
B5,Stirrups Ø10 @50,Hallow ratio 14.8%
2
4
6
8
10
Deflection, mm
B2 ,Stirrups Ø10 @50 Solid
B4,Stirrups Ø10 @50, Hallow ratio 7.4%
B6,Stirrups Ø10 @100,Hallow ratio 14.8%
Figure 17. Comparison of quarter
deflection of all beams.
B1,Stirrups Ø10 @100, Solid
B3,Stirrups Ø10 @100, Hallow ratio 7.4%
B5,Stirrups Ø10 @50,Hallow ratio 14.8%
B2 ,Stirrups Ø10 @50 Solid
B4,Stirrups Ø10 @50, Hallow ratio 7.4%
B6,Stirrups Ø10 @100,Hallow ratio 14.8%
Figure 18. Comparison of central deflection of all beams.
Note: The deflection of all beams at left quarter side are assumed to be the same values on
right quarter side as shown in Figs. 19 to 24.
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Figure 19. Deflection through a long of reinforced concrete beam, B1.
Figure 20. Deflection through a long of reinforced concrete beam, B2.
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Figure 21. Deflection through a long of reinforced concrete beam, B3.
Figure 22. Deflection through a long of reinforced concrete beam, B4.
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Figure 23. Deflection through a long of reinforced concrete beam, B5.
Figure 24. Deflection through a long of reinforced concrete beam, B6.
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An Analysis of Stress Distribution in a Spline Shaft Subjected to Cycilc
Impulsive Load
Ass. Prof. Dr. Fathi A. AL- Shammaa
Department of Mechanical Engineering
University of Baghdad
E-Mail: [email protected]
Hawaa F. Kadhim
Department of Mechanical Engineering
University of Baghdad
E-Mail: [email protected]
ABSTRACT
In this paper the effect of engagement length, number of teeth, amount of applied load, wave
propagation time, number of cycles, and initial crack length on the principal stress distribution,
velocity of crack propagation, and cyclic crack growth rate in a spline coupling subjected to cyclic
torsional impact have been investigated analytically and experimentally. It was found that the
stresses induced due to cyclic impact loading are higher than the stresses induced due to impact
loading with high percentage depends on the number of cycles and total loading time. Also
increasing the engagement length and the number of teeth reduces the principal stresses (40%) and
(25%) respectively for increasing the engagement length from (0.15 to 0.23) and the number of
teeth from (8 to 10). while increasing the other parameters (amount of applied load, wave
propagation time, number of cycles, and initial crack length) increase the principal stresses at the
root of the tooth (37% when the applied load rises from (8 KN to 11KN) and (62% when the wave
propagation time rises from (0.5 to 1).
Key words: spline coupling, cyclic impact, stress distribution, velocity of crack propagation, cyclic crack
growth rate.
‫الخالصة‬
‫ عدد‬,‫ سمه اوتقال المىجت‬,‫ مقدار الحمل المسلط‬,‫ عدد االسىان‬,‫فٍ هذا البحث تم اجزاء دراست عملُت ووظزَت لثأثُز طىل التعشُق‬
ٍ‫ و معدل ومى الشق الدورٌ ف‬,‫ سزعت امتداد الشق‬,‫ والطىل االبتدائٍ للشق علً كل مه تىسَع االجهاداث الزئُسُت‬,‫الدوراث‬
‫ وقد وجد ان االجهاداث الزئُسُت الىاتجت عه الصدمت الدورَت اعلً مه‬.‫وصلت اللزبط المسىىت المعزضت لصدمت دورَت التىائُت‬
‫ وان سَادة طىل التعشُق‬.‫االجهاداث الزئُسُت ال ىاتجت عه صدمت مىفزدة بىسبت عالُت تعتمد علً عدد الدوراث و سمه التحمُل‬
‫)وعدد‬0.23m ً‫ ال‬0.15m( ‫ )علً التىالٍ عىد سَادة طىل التعشُق مه‬%25 %40(‫وعدد االسىان َقلل االجهاداث المتىلدة بىسبت‬
ٍ‫ والطىل االبتدائ‬,‫ عدد الدوراث‬,‫ سمه اوتقال المىجت‬,‫)فٍ حُه سَادة العىامل االخزي (مقدار الحمل المسلط‬10ً‫ ال‬8(‫االسىان مه‬
8(‫ )عىد سَادة الحمل المسلط مه‬%37(‫حُث َشداد‬.‫للشق) تؤدٌ الً سَادة االجهاداث الزئُسُت المتىلدة فٍ وصلت الزبط المسىىت‬
.)1 ً‫ ال‬0.5 ( ‫)عىد سَادة سمه اوتقال المىجت مه‬62%(‫) و‬11KN ً‫ال‬
1.INTRODUCTION
A spline coupling is an effective mode of torque transfer between two rotating parts. It transmits
torque, but permits axial sliding. The spline coupling is used in high torque transmission engines
like vehicles, turbines, and jet engines. The literature that deals with spline coupling has been
investigated experimentally and theoretically in several studies which considered the spline tooth
profile like ; Yeung 1999, Baker 1999, Chitkara et al 2001, and Yang et al 2007, failure analysis
of the spline coupling like: Li et al 2007, Ding et al 2007, Ding et al 2008, and Lin et al2008, and
the stress distribution along the axial direction of a spline coupling under static load like; Taylor
2001, Tjernberg 2001, Barrot et al 2009, and Grath 2009. In the present work the stress
distribution, velocity of crack propagation, and cyclic crack growth rate in a spline coupling
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subjected to cyclic torsional impact load have been investigated analytically and experimentally for
two different boundary conditions.
2.ANALYTICAL ANALYSIS
The torque distribution along the pressure face of the spline coupling tooth was assumed to be
unevenly distributed due to the deformation occurs in the spline teeth which caused during torque
transmitting ,Baker 1999, see Fig. 1.
For a spline coupling subjected to impact load the torque distribution along the axial direction can
be described as; Barrot 2009.
Where;
The coefficients A and B depend on the boundary condition of the spline coupling. Two types of
boundary conditions were studied, in the first type the spline shaft was fixed (built in) at one end
and free at the other and the sleeve was engaged at the free end, so it called (Built in-Free spline
coupling BFSC). In the second type the spline shaft was fixed at both ends and the sleeve was
engaged at the middle of the shaft and it was called (Built in-Built in spline coupling BBSC).
For (BFSC); m (0, t) =0 ,
For (BBSC); m (0, t) =T
m (L, t) =T
,
m (L, t) =T
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The torque transmitted due to cyclic impact load was described as follows;
3. PRINCIPAL STRESS DISTRIBUTION
The principal stress distribution was calculated using the equation ; Mancuso, J.R.,2001
4. VELOCITY OF CRACK PROPAGATION
As the crack propagates the displacement V will change with time. Denoting the rate of change
as ; Ewalds, 1989.
Where;
For steel
= 0.8
5. CYCLIC CRACK GROWTH RATE
Paris' law relates the stress intensity factor rang to sub-critical crack growth rate. The basic formula
reads;
The term in the left hand side known as the crack growth rate under cyclic loading regime is called
cyclic crack growth rate. On the right hand side
and m are material constants, and ΔK is the
range of the stress intensity factor.
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For an edge crack in an infinite sheet Y=1.12, Ewalds, 1989.
For steel m=3 and
is 10-11, David R., 2001, see Fig.2.
6. EXPERIMENTAL WORK
A spline coupling models of ST-45 simulate the spline coupling of a Power Take-Off engine have
been manufactured at the manufactory of "THE STATE COMPANY OF MECHANICAL
INDUSTRES" with two number of teeth (8 and 10) and three engagement lengths
(0.08m,0.15m,0.23m). The spline coupling samples were manufactured in two groups the first
group suitable to set as (BBSC) and the second group suitable to set as (BFSC). The test rig
consisted of fixing plate which is a heavy rectangular base with two vertical plates. At the upper end
of each vertical plate there is a circular hole to carry and fix the spline coupling samples. The
impactor which consisted of two arms connected to a disc. The disc had a several holes around its
circumference each hole represented a different winding angle which causes a different amount of
load. The disc was connected to a helical spring, see Fig. 3. The strain induced at the root of the
spline coupling tooth was measured using strain gauges connected to a sensor circuit to convert the
change in resistance into change in voltage and amplify the strain gauge output signal. The output
signal of the sensor circuit goes to a digital data logger, (ORDEL UNIVERSAL DATA LOGGER
(UDL 100)), to record the data and the display and save them on a computer, see Fig. 4.
7. ANALYTICAL RESULTS
Theoretical investigation is done for two loading cases (impact load and cyclic impact load), two
boundary conditions (BBSC and BFSC), three engagement lengths (0.08m,0.15m,0.23m), and three
amounts of applied load (5 kN, 8 kN, 11 kN). Fig. 5 shows that the principal stress distributes
exponentially along the axial direction of the BFSC tooth and that the principal stresses induced in
the spline shaft are higher than the principal stresses induced in the sleeve because of the difference
between their geometry especially their root radiuses. Fig. 6 shows that the principal stress
distributes exponentially along the axial direction of the BBSC tooth and it distributes evenly due to
the symmetric boundary conditions at its both ends. Fig. 7 shows that the principal stresses induced
due to applying cyclic impact load are higher than the principal stresses induced due to applying
impact load with high different percentage depends on the number of cycles per unit time and the
total loading time. The increasing in stresses results from accumulating the stresses induced at each
cycle. Fig. 8 shows that increasing the amount of the applied load increases the induced principal
stresses and the increasing is linear because the stresses are linearly related to the amount of applied
load. Fig. 9 shows the significant effect of the engagement length on the principal stresses where it
shows that increasing the engagement length reduces the principal stresses with a high ratio due to
increasing the area that carries the load. Fig. 10 shows that increasing the number of teeth reduces
the induced principal stresses due to dividing the applied load on a higher number of teeth and
hence each tooth carries fewer load. Fig. 11 shows that the principal stresses increases
exponentially with the wave propagation time and 62% of this increasing occurs between (t/to =0.5
to t/to =1). Fig. 12 shows that the behavior of the velocity of crack propagation is similar to the
behavior of the principal stresses with respect to time. That is because the velocity of crack
propagation depends on the principal stress values. Also Fig.12 shows that increasing the number of
cycles increases the velocity of crack propagation due to increasing the accumulated stresses. Fig.
13 shows that the cyclic crack growth rate increases with increasing the number of cycles, this
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increasing occurs due to increasing the accumulative stresses from each cycle. Fig. 14 shows that
the cyclic crack growth rate increases with high percentage with increasing the initial crack length
because of increasing the energy released from the tooth. The energy released causes energy
concentration at the tip of the crack which results in increasing the principal stresses at the tip of the
crack that’s results in increasing the cyclic crack growth rate.
8. EXPERIMENTAL RESULTS
Fig. 15 shows that increasing the amount of the applied load increases the induced principal stresses
and this increasing is linear. Fig. 16 shows that at the fixed end of the spline coupling the effect of
the amount of the applied load on the induced principal stresses is the same for (BBSC) and
(BFSC). Fig. 17 shows that increasing the number of the spline coupling teeth reduces the induced
principal stresses due to distribute the load over a higher number of teeth hence each tooth carries
less load. Fig. 18 shows that increasing the engagement length have a significant effect in reducing
the induced principal stress because of increasing the area carries the load. Fig. 19 shows that the
stresses induced due to cyclic impact load are higher than the stresses induced due to impact load
with a high percentage depends on the number of cycles per unit time and the total loading time.
Fig. 20 shows that increasing the number of cycles results in increasing the velocity of crack
propagation due to increasing the accumulative stresses that accumulates from each cycle. Fig. 21
shows that the cyclic crack growth rate increases exponentially with the increasing of the number of
cycles, this increasing occurs due to the increasing of the accumulative stresses.
9. VERIFACATION
The experimental results verified the theoretical results and showed a good agreement with
reasonable error percentage comes from the delay time of the response of the measuring instruments
therefore this error percentages increase as the impact wave propagates faster due to increasing the
delay time. Fig. 22 shows that the experimental results of the principal stress variation with the
amount of applied load coincides with the theoretical results with an error percentage equals to
(9%). Fig. 23 shows that the experimental results of the velocity of crack propagation variation with
the wave propagation time coincides with the theoretical results with an error percentage equals to
(9%). Fig. 24 shows that the experimental results of the cyclic crack growth rate variation with the
number of cycles coincides with the theoretical results with an error percentage equals to (10%).
10. CONCULUSIONS
1. The principal stresses induced in the spline shaft are different from the principal stresses
induced in the sleeve with a percentage depends on their geometry.
2. The end of the engagement length endures the maximum stress and it’s the most susceptible
point to failure.
3. In the BBSC both ends endures the maximum stresses while in the BFSC only one end
endures the maximum stresses.
4. The engagement length has a significant effect on reducing the stresses.
5. The time of wave propagation of the cycling impact loads wave have a very significant
effect on the stresses induced in the spline shaft then the impact loads.
6. Appling cyclic impact load on the spline coupling highly raises the velocity of crack
propagation.
7. The cyclic growth rate obeys Paris law.
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NOMENCLUTURE
Symbol
A:
B:
C:
N:
L:
W:
w:
X:
m:
.n:
Z:
k:
K:
T:
t:
meaning
coefficient
coefficient
spline tooth height
number of teeth
engagement lengt
spline tooth width
applied load
axial posision
material coefficient
number of cycles
half crack length
integral constant
stress intensity factor
applied torque
instantaneous wave propagation time
total wave propagation time
Unit
#
#
Mm
#
mm
mm
applied load
mm
#
Cpm
mm
#
Mpa
KN.m
Sec
Sec
E:
Cpm:
G:
a:
:
:
:
:
:
:
:
modulus of elasticity
cycle per minute
modulus of rigidity
crack length
Initial crack length
instantaneous crack length
material coefficient
sleeve root radius
shaft root radius
sleeve outer radius
spline coupling pitch radius
Kn.m
cycle/min
KN.m
mm
mm
mm
#
mm
mm
mm
mm
:
:
P(x):
sleeve polar moment of inertia
:
:
:
m(x,t):
Kn.m:
V:
:
α:
:
:
:
:
shaft polar moment of inertia
static presser
torque transmitted by sleeve
Torque transmitted by shaft
torque transmitted by
transmitted torque
Spline coupling
velocity of crack propagation
impact velocity of crack
coefficient
material density
poison's ratio
principal stress
torsional rigidity
Kpa
Kn.m
Kn.m
Kn.m
Kn.m
due to cyclic impact load
m/sec
m/sec`
N/rad
Kg/
#
KN/
KN/rad
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:
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principal stress due to
cyclic impact load
sleeve angle of twist
shaft angle of twist
rad
rad
REFERANCES
Ali, M.A., 2009,A Study of a Delimitation Problem in a Leaf Spring Made of Composite
Material under Impact Load, M.Sc. Thesis, University of Baghdad, Baghdad.
Baker, D.A, 1999, A Finite Element Study of Stresses in Stepped Spline Shafts and Partially
Splined Shafts under Bending, Torsion And Combined Loadings", M.Sc. Thesis, Virginia
Polytechnic Institute , State University, Virginia.
Barrot, A., Paredes, M., and Sartor. 2009, Extended Equations of Load Distribution in the Axial
Direction in a Spline Coupling, Journal of Engineering Failure Analysis, Vol. 16, P.P. 200-211.
Darrell, F.S., and Gary, B.M., 2000,Multiaxial Fatigue, SAE,Inc.
David, Roylance, 2001,, Fatigue, Department of Materials Science and Engineering,
Massachusetts Institute of Technology, Cambridge, MA 02139.
Ding, J., Leen, S.B., Williams, E.J., and Shipway, P.H., 2008, Finite Element Simulation of
Fretting Wear-Fatigue Interaction in Spline Couplings, Journal of Tribology, Vol.2, No. (1).
Ding, J., McColl, I.R., Leen, and S.B., 2007, The Application of Fretting Wear Modeling To a
Spline Coupling, Journal of Wear,Vol.262, P.P.1205-1216.
Ewalds, H.L., and Wanhill, R.J.H. 1989, Fracture Mechanics, Edward Arnold.
Grath, J.P., 2009, Analysis of Axial Load Distribution in a Jet Engine Disk-Shaft Spline
Coupling, M.Sc. Thesis, Faculty of Rensselaer Polytechnic Institute.
Hall, A.S., Holowenko, A.R., and Laughlin, H.G., 1961, Theory and Problems of Machine
Design, Schaum's outline, Mc-Graw Hill, Inc.
Hearn, E.J., 2000, Mechanics of Materials1, Butterworth Heinemann.
Johanson, W. 1972, Impact Strength of Materials, Edward Arnold.
Jonas, A.Z., Theodore, N., Hallock, F.S., Longin, B.G., and Donald, R.C., 1982, Impact
Dynamics, John Wiley Sons.
Li, Y.J., Zhang, W.F., and Tao, C.H., 2007, Fracture Analysis of Castellated Shaft Journal of
Engineering Failure Analysis, Vol.14, P.P.573-578.
Lin, C., Hung, J., and Hsu, T., 2008, Failure Analysis of Reverse Shaft in the Transmission
System of All-Terrain Vehicles, Journal of Fail. Anal. and Prevent. , Vol. 8, P.P. 75-80.
Mancuso, J.R., and Jones, R., 2001, Coupling Interface Connection
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2014
Journal of Engineering
Naser Shabakhty, 2004, Durable Reliability of Jack-up Platforms, Ph.D. Thesis, Delft
University of Technology, Netherlands.
Sowrappa, L.R., 2005, Laminated Architecture Glass Subjected to Blast, Impact loading,
Patricio, M., and Mattheji, R.M.M., 2002, Crack Propagation Analysis.
Shigly, 2006,Mechanical Engineering Design, Mc-Grow Hill Inc., eighth edition.
Tariq, M.H., 2008,The Effect of Low Velocity Impact with Fatigue Loading on Cracked
Rectangular Plate M.Sc. Thesis, University of Baghdad, Baghdad.
Taylor, J.W., 2001, Modeling and Simulation of Spline Couplings, United Kingdom.
Tjernberg, A., 2001, Load Distribution and Pitch Errors in a Spline Coupling, Journal of
Materials and Design, Vol.22, P.P.259-266.
Varin, J.D., 2002,Fracture Characteristic of Steering Gear Sector Shaft, Journal of Practical
Failure Analysis, Vol.2, No.(4), P.P.65-69.
Yang, D.C.H., and Tong, s., 2007, On the Profile Design of Transmission Splines and Keys
Journal of Mechanism and Machine Theory, Vol.42, P.P.82-87.
Yeung, K.S., 1999, Analysis of a New Concept in Spline Design for Transmission Output
Shafts", Ford Motor Company, Dearborn, MI, 24121, USA.
http://en.wikipedia.org/wiki/Paris'_law
http://en.wikipedia.org/wiki/Spline-(mechanical)
http://www.facebook.com/pages/Rotating-spline/143902598956699?sk=wiki
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Figure 4. The measuring instruments.
Figure 1. Schematic figure of the spline
coupling.
.
Figure 2. Schematic plot of the typical
relationship between the crack growth rate
and the range of the stress intensity.
Figure 5. Principal stress distribution
along the axial direction of a (bfsc) tooth due
to impact load.
Figure 3. The fixing plate and the impact.
Figure 6. Principal stress distribution along a
(bbsc).
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Figure 10. Stress distribution along a (bbsc)
sleeve for 3 different engagement lengths.
Figure 7. Effect of cyclic impact load on the
principal stress values.
Figure 11. Stress distribution along a (bbsc)
sleeve for 3 different numbers of teeth.
Figure 8. Principal Stress Distribution along a
(BFSC) Sleeve for 3 Different Cyclic Loads.
Figure 12. Stress distribution along a (bfsc)
sleeve at 4 different wave propagation times.
Figure 9. Principal stress distribution along a
(bfsc) sleeve for 3 different cyclic loads.
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n=4 cpm
n=6 cpm
n=8 cpm
n=10 cpm
Vc (m/sec)
BBSC,load=11KN,L=0.23m,N=6,x=0.2m
n=12 cpm
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
0
0.5
1
1.5
(t/to)
Figure 16. Principal stress variation with
amount of applied load.
Figure 13.Velocity of crack propagation due
to cyclic impact load for 5 different numbers
of cycles.
Figure 17.Principal stress variation with the
amount of applied load for 2 different number
of teeth.
Figure 14. Cyclic crack growth rate variation
with number of cycles.
BBSC,(t/to)=0.5,L=0.23m,N=6,load=11KN
sleeve
shaft
da/dn (m/cycle)
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
0
5
10
15
20
25
(n)
Figure 18. Principal stress variation with the
engagement length.
Figure 15. Cyclic crack growth rate for 4
different initial crack lengths.
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Figure 19. Principal stress variation with the
amount of applied load for impact and cyclic
impact load.
Figure 22.Comparison between the
experimental and theoretical results for the
principal stress variation with the amount of
cyclic impact load.
Figure 20. Variation of velocity of crack
propagation with wave propagation time for 2
different numbers of cycles.
Figure 23. Comparison between the
experimental and theoretical results of
velocity of crack propagation variation with
the wave propagation time.
Figure 21. Cyclic crack growth rate variation
with the number of cycles.
Figure 24. Comparison between the
experimental and theoretical results of the
cyclic crack growth rate variation with the
number of cycles.
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Study of Dynamic Sorption in Adsorption Refrigeration Cycle
Adil A. Al-Hemiri
Proffessor
Eng. College
Baghdad University
E-mail : [email protected]
Mohammed A. Atiya
Assistant Professor
Research & Development Department
Ministry of Higher Education & S.R.
E-mail : [email protected]
Farkad A. Lattieff
Assistant instructor
Research & Development Department
Ministry of Higher Education & S.R.
E-mail : [email protected]
ABSTRACT
This paper shows the characteristics of temperature and adsorbed (water vapor) mass rate
distribution in the adsorber unit which is the key part to any adsorption refrigeration system. The
temperature profiles of adsorption/desorption phases (Dynamic Sorption) are measured
experimentally under the operating conditions of 90oC hot water temperature, 30oC cooling
water temperature, 35oC adsorption temperature and cycle time of 40 min. Based on the
temperature profiles, The mass transfer equations for the annulus adsorbent bed are solved to
obtain the distribution of adsorption velocity and adsorbate concentration using non-equilibrium
model. The relation between the adsorption velocity with time is investigated during the process
of adsorption. The practical cycles of adsorption and desorption were stated dependent on the
variables obtained from the experiment and equations calculations.
The results show that the adsorption velocity is diminished after a period of 20 min. The
maximum value of the adsorbed water vapor concentration on silica gel is 0.12 kg water/kg
adsorbent (adsorption phase) and the minimum value of the water content into silica gel is 0.04
kg water/kg adsorbent (desorption phase) producing a dynamic sorption of
kg
water/kg adsorbent.
Key words: adsorption, refrigeration, silica gel-water, mass transfer
‫دراست ديناميكيت االمزاا في دورة الزبريذ اآلمزاا يت‬
‫م فرقذ علي لطيف‬.‫م‬
‫دائزة انبحذ ٔانخطٌٕز‬
ًً‫ٔسارة انخعهٍى انعانً ٔانبحذ انعه‬
‫ محمذ عبذ عطيت‬.‫د‬.‫م‬.‫ا‬
‫دائزة انبحذ ٔانخطٌٕز‬
ًً‫ٔسارة انخعهٍى انعانً ٔانبحذ انعه‬
‫ عادل احمذ عوض‬.‫د‬.‫ا‬
‫كهٍت انُٓذست‬
‫جايعت بغذاد‬
‫الخالصت‬
‫ٌعزض ْذا انبحذ خصائض حٕسٌع انحزارة ٔجزٌاٌ انكخهت نهًادة انًًخشة (بخار انًاء) فً ٔحذة اَيخشاس ٔانخً حًزم‬
‫ إٌ شكم انخٕسٌع انحزاري ألطٕار اَيخشاس ٔاالَبعاد (دٌُايٍكٍت االيخصاص) حى‬.‫انجشء انًفخاح َي يُظٕيت حبزٌذ أيخشاسٌت‬
‫و نهًاء انبارد ٔدرجت حزارة‬o 30 ‫و نهًاء انساخٍ ٔدرجت حزارة‬o 90 ‫قٍاسّ عًهٍا" ححج ظزٔف حشغٍهٍت يٍ درجت حزارة‬
‫ اعخًادا عهى شكم انخٕسٌع انحزاري فأٌ يعادالث اَخقال انًادة نحشٕة انحبٍباث‬.‫ دقٍقت‬40 ‫و ناليخشاس ٔسيٍ دٔرة‬o 35
ٍٍ‫ كذنك انعالقت ب‬.ٌ‫انذائزٌت قذ حهج نهحصٕل عهى حٕسٌع سزعت االيخشاس ٔحزكٍش انًادة انًًخشة باسخعًال يٕدٌم انالحٕاس‬
‫ حى ححذٌذ انذٔرة انعًهٍت ناليخشاس ٔاالَبعاد باالعخًاد‬.‫حغٍز سزعت االيخشاس يع انشيٍ قذ حى انخحقق يُٓا إرُاء عًهٍت االيخشاس‬
.‫عهى عهى انًخغٍزاث انخً حى انحصٕل عهٍٓا يٍ انخجزبت ٔحساباث انًعادالث‬
0112 ‫ كاَج أعهى قًٍت نخزكٍش بخار انًاء انًًخش فً انسهٍكا جم‬. ‫ دقٍقت‬20 ‫انُخائج بٍُج اٌ سزعت االيخشاس حخالشى بعذ يزٔر‬
"‫كغى ياسِ فً انسهٍكا جم ( إرُاء االَبعاد) يٕنذة‬/‫ كغى ياء‬0104 ‫كغى ياسِ ( إرُاء االيخشاس) ٔأٔطأ قًٍت كاَج‬/‫كغى ياء‬
.ِ‫كغى ياس‬/‫ كغى ياء‬0108 ‫دٌُايٍكٍت ايخشاس‬
‫ اَخقال انًادة‬1‫ياء‬-‫ انسٍهكا جم‬1‫ انخبزٌذ‬1‫ االيخشاس‬: ‫الكلماث الرئيسيت‬
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1. INTRODUCTION
Adsorption (solid–vapor) refrigeration is analogous to liquid–vapor absorption, except the
refrigerant is adsorbed onto a solid desiccant (freeze dried) rather than absorbed into a liquid
(dissolved) as in liquid– vapor heat pumps. The adsorption cycle Fig. 1 proceeds as follows
Lambert, 2007.
1. At state 1, a cool canister filled with adsorbent, an adsorber, is saturated with refrigerant at
slightly below Pe. The adsorber is heated and desorbs refrigerant vapor isosterically (i.e., at
constant total mass in the adsorber), pressurizing it to state 2, slightly above Pc ,which opens a
one-way valve to start pumping refrigerant vapor into the condenser.
2. Isobaric heating desorbs more refrigerant, forcing it into the condenser until state 3 is attained,
at which the adsorber is nearly devoid of refrigerant.
3. The hot adsorber is then cooled isosterically (at constant total mass) causing adsorption and
depressurization, until the pressure drops below Pe (state 4), opening another one-way valve
to allow refrigerant vapor to enter the adsorber from the evaporator.
4. Isobaric cooling to state 1 saturates the adsorbent, completing the cycle.
Figure 1. Thermodynamic cycle of the adsorption refrigeration ,Lambert, 2007.
Wang, D., 2014, showed that the adsorption capacity of the silica gel was influenced by many
factors. But pollution by solid particulates was the primary factor to decline the adsorption
capacity.
Aristov, et al., 2012, investigated, using an intermittent cycle, the effect of the relative
duration isobaric adsorption/desorption stages to maximize the coefficient of performance and
the specific cooling power of the cycle. They found that the desorption phase is faster than the
adsorption one and this should be considered as a routine case for adsorption refrigeration cycles,
probably, because desorption occurs at higher temperature and pressure and hence, they
suggested practical
Sapienza, et al., 2012, used a new composite sorbent to operate at low regeneration
temperature (< 70oC). Adsorption equilibrium measurements demonstrated that the new
composite, LiNO3 / Vermiculate exchange about 0.4 kg water/kg adsorbent in an exceptionally
narrow temperature range, 33-36oC (Adsorption at 12.6 mbar) and 62-65oC (desorption at 56.2
mbar).
Gong et al., 2011, evaluated the composite material based on lithium chloride on silica gel as
adsorbent and water as adsorbate in an adsorption chiller. The theoretical results showed that the
COP can be increased using composite adsorbent.
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Demir, et al., 2009, studied the effect of the granule size on the heat and mass transfer. The
decrease of granule size enhances the contact area between the granules and consequently heat
transfer rate through the bed; however it causes the increase of the mass transfer resistance.
Doau, et al., 2006, report results from an open cycle investigation aimed to determine the
optimal salt content of CaCl2 on the silica gel. The sorption equilibrium demonstrated that these
materials can sorb 0.5-0.6 kg water/kg adsorbent at 12.3 mbar and 20oC.
In porous media, adsorption process is controlled by both adsorbate transportation and
diffusion in adsorbent and inner reaction with adsorbent, between the two items, the
transportation of gaseous adsorbate in the tunnel of micro pores and diffusion on its surface are
more dominated than the internal reaction in rare pressure ,Wang, and Wang, 2005.
Aristov, et al., 2002, studied the adsorption capacity of selective water sorbents by confining
hygroscopic salt into the open pores of silica gel. The experimental results showed that the water
uptake of CaCl2 –in-silica gel was about 0.75 kg/kg at the temperature of 28oC while for silica
gel is 0.1 kg/kg.
In this study, the attentions are focused on the mechanisms of mass transfer in the adsorbent
bed of adsorption refrigeration system. The influences of temperature and cycle time on the
adsorption velocity and adsorbate concentration rate are calculated. The governing equations for
the mass transfer are presented and the solution method is described. The results are discussed
via figures, which show the variations of temperature, adsorption velocity, and adsorption
concentration in a circular bed. Finally, the practical cycle of the dynamic sorption is stated
depicting all the operating conditions affected on the system.
2. ADSORPTION CAPACITY TEST
Brazilian commercial mesoporous and microporous silica gel was employed as the adsorbent
for the adsorption chiller prototype Table1.. water free from any ions was chosen as a
refrigerant. For the heating/cooling system, water is the best heat transfer fluid (HTF), with the
highest Cp of any liquid and higher thermal conductivity than all.
The silica gel was saturated whenever it was regenerated in an electric oven at 120 °C for a
minimum period of 24 h. After regenerating the silica gel, the adsorber was replaced
immediately and was expected to cool down to room temperature, at which time and every one
hour, it was weighed on a digital scale with a minimum accuracy of 5 g. The adsorptive
adsorbers are coupled to the evaporator, which is a cylindrical container with a globe type valve
used to control the passage of the adsorbate Fig.1.. Before introducing water vapor from the
evaporator into the adsorber, the vapor pipe from the evaporator toward the adsorber is
evacuated to remove any traces of condensed water vapor, which cause experimental errors. The
difference in weight of adsorber with silica gel before and after the adsorption interval period is
the adsorbed water concentration.
Table. 1 Thermophysical properties of silica gel (values supplied by the manufacturer) .
Property
Value
Unit
Apparent density
750
Kg/m3
Average particle diameter
7
mm
Specific surface area
650-700
m2/g
Thermal conductivity
0.198
W/m.K
Specific heat capacity
921
J/kg.K
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Figure 1. Equilibrium adsorption capacity apparatus.
3. DESCRIPTIONAND PROCEDURE OF EXPERIMENTAL PROTOTYPE
Fig. 2 shows photographs of the experimental adsorption chiller prototype. The adsorption
chiller has a single bed, a condenser, an evaporator and a heating/cooling water system. The
evaporator lies at the bottom of the chiller and the condenser is located at the upper side. The
heating system is next to the adsorber. All the valves are controlled manually. The prototype is
designed to test various operating conditions and operating adsorption cycle. The whole
prototype is connected to a water heating system for regeneration, tap water for cooling and
adsorption, and a vacuum pump.
The main parameter was measured during the experiment: temperature variation with time.
All sensors were connected to a data logger and recorded every 8.5 seconds. The data
measurements were taken after the cycle steady state had been reached. A computer was used to
collect and process the measurement data acquired by the data logger. The flow rate of hot water
and cooling water are constant at 0.04 kg/s.
Fig. 3 illustrates the schematic diagram of the testing system. The adsorber is of the shell and
fin-tube configuration which is readily (easily) manufactured, and it can withstand high
operating pressure and incur low inert mass. The principle innovation of this design is that of
internal heat exchanger of the adsorber. Using fins and tubes made the surface area to volume
ratio relatively large. The fins on the adjacent four tubes overlap slightly in order to reach all
portions of the shell void.
To complete one full cycle, the adsorbent bed passes through four consecutive steps: preheating, desorption, precooling, and adsorption. In the adsorber, about 4 kg silica gel is filled.
The hot water temperature can be controlled in the range of 85–90oC. The flow rate of hot water
is controlled by valve V7 and the cooling water is controlled by V8. V1 and V2 controlled the
flow of the refrigerant from the adsorber to the condenser (desorption) and from the evaporator
to the adsorber (adsorption), respectively. Table. 2 reports the operating conditions of the tested
adsorber where all the investigated tests conditions are displayed in terms of temperature and the
duration of cycle time.
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Figure 2. Pictorial of the experimental device.
Valve 1
Refrigerant vapor
Valve 6
Vacuum pump
Pressure transducer
Condenser
Fins &tube HEX
Data logger
Valve 2
Adsorber
Heating
Water system
Valve 3
Valve 7
Flask
Computer
Valve 8
Valve 4
Tap water
Evaporator
Figure 3. The schematic diagram of the experimental adsorption chiller.
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Table 2. Experimental parameters for single bed silica gel-water prototype
Parameter
Value
11.2oC
30oC
35oC
90oC
1.25 min
1.25 min
18.75 min
18.75 min
40 min
4. NON-EQUILIBRIUM ADSORPTION MODEL
For refrigeration applications, the adsorbent should have high adsorptive capacity at ambient
temperature and low pressure, and small capacity of adsorption at high temperature and pressure
,Leite, et al., 2004. Two types of mass transfer are encountered in a granular adsorbent bed :
mass transfer within the adsorbent granules and mass transfer through the void between the
granules (i.e intra-particale and inter-particle mass transfer) , Demir et al., 2009. The
equilibrium adsorption quantity is the amount of refrigerant adsorbed by the sorbent when the
reaction time tends towards infinite, and it is an important parameter for adsorption working
pairs. In general, the velocity of adsorption in adsorber is not faster than that of heat transfer, that
is, the desorption rate does not reach the equilibrium value at each status point in real operation
,Wang, and Wang, 2005. Moreover, the actual process of adsorption/desorption is of nonequilibrium and it actually relies on the mass transport process. Therefore, actual adsorption
process is not the process only dominated by the temperature of adsorbent and pressure of the
adsorbate, it is involved with mass transport and diffusion, Wang, and Wang, 2005.
The equilibrium model for this physical adsorption concentration ( ) is a function of
adsorbent temperature and pressure, and it is written in a generic form as, Liu, et al., 2005.
Models with different fixed parameters are as follows:
These functions correlate the temperature T, the pressure P and the concentration of the
adsorbed phase , so that ƒ (T, P, ) = 0 For equilibrium of adsorption in micrporous materials
with a polymodel distribution of pore dimensions, such as the silica gel-water and activated
carbon-methanol pair, Dubinin and Astakohov proposed the following isotherms, Dieng, and
Wang, 2001.
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(
(
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)) ]
Where:
Sakoda and Suzuki, (1984) considered the influence of diffusion on the micropores surface,
proposed the model of adsorption velocity as below (2). When the analysis is simplified, the
lagging effect between adsorption and desorption is neglected:
(
)
(
)
The saturation vapor pressure and temperature are correlated by Antonio's equation which can
be written as ,Khan, et al., 2006.
(
(
))
Firstly, the equilibrium adsorbate concentration within the adsorbent granule is evaluated by
using Eq. (1) at the specified temperature and pressure Eq. 5. Eq. (4) is solved to find the
adsorption rate constant. Based on all these calculations, Eq. (3) and Eq. (4) are solved to find
the adsorption velocity and the simultaneous concentration distribution. An iteration is
performed before increasing a time step. The iteration is continued until the time of the phase is
completed.
5. RESULTS AND DISSCUTION
The adsorption isotherm of water on silica gel (Brazilian type) is presented in Fig. 4.The
experimental results include equilibrium water uptake when the silica gel was exposed to
saturated water vapor at operating temperature, 30oC. It is shown that the maximum equilibrium
adsorption capacity is 0.2 kg water \ kg adsorbent.
Fig. 5 shows the temporal evolution of the isosteric cooling, isosteric heating, desorption and
adsorption cycles at a steady state for the following operating conditions concluded from the
experiment test.
The adsorption rate constant decreased when temperature was lowered, which means that the
adsorption was taking longer time at lower temperatures, Fig. 6.
Fig. 7 shows the time change in the amount of adsorbed water vapor measured at various
regeneration temperatures. As seen in this figure, the amount of adsorbed water increases with
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time for the same temperature, but decreases with regeneration temperatures. However, effective
adsorptivity did not reach the value equal to maximum state recorded from experimental results
of water adsorption isotherm of silica gel, ; e.g. at 30oC,
is 0.13 kg/kg for 20 min, whereas
is 0.2 kg/kg. Using these results, it was determined that 35 % of silica gel was not effectively
used in cycle operation.
The experimental values of the adsorption velocity (dx/dt) as a function of adsorption time
using a single adsorber bed are reproted in Fig. 8. The operating conditions selected are the
following:
=30oC,
=35oC, and
=90oC. Results obtained demonstrated that the
adsorption velocity was diminshed after 20 mins. There is a very low value of adsorption
velocity after 20 mins, and it may not be enough to keep the temperatre of the water inside the
evaporator at the designed value.
Desorptoin process is very close in concentration change to adsoption process, and many
researches assume both are the same in adsorption refrigeration process. It is clear from
experimental results that after 20 mins, the concentration of water into silica gel reaches 0.048 kg
water/kg adsorbent Fig. 9. It is vey close to the calculated value, 0.04 kg/kg, by using Eq. (3)
Fig 10.
Based on this non-equilibrium model Eq.(3), some calculations using experimental results
have been done to discover the effect of non-equilibrium adsorption on adsorption refrigeration
Fig. 10. It could be observed that the non-equilibrium deviates from the equilibrium particularly
for a time shorter than 40 min., and for the first time, this deviation does not seem very big. For
example, the value of non-equilibrium adsorption rate at 20 min. is 0.12 kg/kg while for the
equilibrium rate; it is 0.124 kg/kg. This difference of 0.004 kg water/kg adsorbent can produce a
cooling power of 9.908 kJ/kg adsorbent. Without doubt, the non-equilibrium model is closer to
the real process of adsorption refrigeration and should not be neglected on designing cycle
adsorption chiller, especially when the cycle is short because in real short cycle, the adsorbed
refrigerant could not be sufficient due to the non-equilibrium adsorption process , Wang and
Wang, 2005. In the same figure Fig. 10. , the non-equlibrium desorption process is very close to
the equilibrium and the reason is simply because of the high rate constant of the desorption
process.
Fig. 11 aims to determine the dynamic water sorption, which represents the amount of water
involved in one adsorption-desorption cycle. The experiment has consisted of loading adsorbent
with water under a temperature of 35oC, then the adsorbent were, afterwards, desorbed at the
temperature of 90oC in the same duration as the adsorption time. The difference between
adsorbent loading at the end of the adsorption, = 0.12 kg/kg, and its loading at the end of
desorption, = 0.04 kg/kg, constitutes the dynamic water sorption.The measurment of the
adsorpion capacity of this type of silica-gel showed that it is able to exchange a large amount of
water of 0.08 kg/kg under operating conditions so it is typical for air conditioning applictions as
well as to be driven by hot water temperaure of 90oC.
A complete cycle of adsorption/desorption for the silica gel-water adsorber is shown in Fig.
12. During the adsorption phase, the maximum value reached is 0.12 kg/kg after the first halfcycle of 20 mins, and the minimum is 0.04 kg/kg during the second half-cycle of 20 mins. this
value is perhapes the target to get the best performance of the system.
To demonstrate the practical cycle of adsorption chiller using a silica gel-water system, Fig
13 presents the calculated data using Eqs. (1-5) at two worked isobar pressure ranges, namely the
vapor pressure of evaporator ( = 7oC, Pe = 1 kpa), A-D curve, and the condenser ( =30oC, Pc
= 4.2 kpa), B-C curve, where A-B and C-D lines represent isostering cooling and heating phases
respectively. Measuring isobars of water adsorption/desorption is useful for drawing a temporary
cycle of the adsorptive chiller and determining the boundary temperatures for the adsorption and
desorption processes. Isobars of water adsorption at P = 1 kpa and desorption at P = 4.2 kpa
165
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measured for the sorpent of silica gel-water represent the isobric stages of a typical chiller cycle
Fig 6.12. The highest desorption temperature was fixed at 90oC, that determined the content of
the water, with = 0.04 kg/kg. Desorption of water started at 60.5oC, and finished at 90oC
(isobar line B-C). The lowest adsorption temperature of 35oC resulted in the maximal adsorbed
amount of = 0.124 kg/kg. Adsorption of water started at 62oC, and finished at 35oC (isobar line
D-A). This shows the properties of this type of silica gel to exchange 0.084 kg/kg is very close to
the experimantal result obtained by the practical test work Fig. 11. As mentioned above, Fig. 13
will help us to assess the level of temperatures of alternating adsorption to desorption and vice
versa, but it is still not able to compare it with the experimental cycle because there is no
instrument that can measure the change of water concentration into silica gel with the
temperature directly.
5. CONCLUSIONS
The mass transfer in a cylindrical annulus bed packed with silica gel granules during the
adsorption/desorption process were analyzed. The measurement of adsorption rates using a nonequilibrium model shows that this type of silica gel is able to exchange an amount of 0.08 kg
water/kg adsorbent under the operating conditions of 90oC desorption temperature, 35oC
adsorption temperature, and cycle time of 40 min. the practical cycle indicated that the system
has the ability to work under different operating system due to its dynamic sorption variation.
Thus, this type of adsorbent should be a good candidate for various thermal applications driven
by low temperature heat sources.
REFERENCES
- Aristov Y.I., Sapienza A., Ovoshchnikov D.S., Freni A., and Restuccia G., 2012. Reallocation
of Adsorption and Desorption Times for Optimisation of Cooling Cycles. Internal journal of
refrigeration, Vol. 35, PP. 525-531.
- Aristov Y.I., Restuccia G., and Parmon V.N.,2002, A Family of New Working Materials for
Solid Sorption Air Conditioning Systems, Applied thermal engineering, Vol. 22, PP.191-204.
- Dauo K., Wang R.Z., and Xia Z.Z., 2006, Development of a New Synthesized Adsorbent for
Refrigeration and Air Conditioning Applications, Applied Thermal Engineering, Vol. 26, PP.
56-65.
- Demir H., Mobedi M., and Ulku S., 2009, Effect of Porosity on Heat and Mass Transfer in a
Granular Adsorbent Bed, International communications in Heat and Mass Transfer, Vol. 36,
PP. 372–377.
-
Dieng A.O., and Wang R.Z., 2001, Literature Review on Solar Adsorption Technologies for
Ice-Making and Air Conditioning Purposes and Recent Developments in Solar Technology.
Renewable and Sustainable Energy Reviews, Vol. 5, PP. 313–342.
- Gong L.X., Wang R.Z., Xia Z.Z., Chen C.J., 2011, Design and Performance Prediction of a
New Generation Adsorption Chiller Using Composite Adsorbent, Energy Convers Mange,
Vol. 52, PP. 2345-50.
- Khan M.Z.I., Alam K.C.A., Saha B.B., Hamamoto Y., Akisawa A., and Kashiwagi T., (2006),
Parametric study of a Two-Stageadsorption Chiller using Re-Heat-the Effect of Overall
166
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2014
Journal of Engineering
Thermal Conductance and Adsorbent Mass on System Performance. International Journal of
Thermal science, Vol. 45, PP. 511-519.
- Lambert M. A., 2007, Design of Solar Powered Adsorption Heat Pump with Ice Storage,
Applied Thermal Engineering, Vol. 27, PP. 1612–1628.
- Leite A.P., Grilo M.B., Belo F.A., and Andrade P.R., 2004, Dimensioning, Thermal Analysis
and Experimental Heat Loss Coefficients of An Adsorbtive Solar Icemaker, Renewable
Energy, Vol. 29, PP. 1643-1663.
- Liu Y.L., Wang R.Z. and Xia Z.Z., 2005. Experimental Performance of a Silica Gel–Water
Adsorption Chiller. Applied Thermal Engineering, Vol. 25, PP. 359–375.
- Sapienzaa A.l., Glaznevb I.S., Santamariaa S.A., Frenia A.N., and Aristov Y.I., 2012,
Adsorption Chilling Driven by Low Temperature Heat: New Adsorbent and Cycle Optimization,
Applied Thermal Engineering, Vol. 32, PP.141-146.
-
Wang D., Zhang J., Yang Q., Li N., and Sumathy K., 2014, Study of Adsorption Characteristics in
Silica Gel–Water Adsorption Refrigeration, Applied Energy, Vol.113, PP.734–741.
- Wang, W. and Wang, R., 2005, Investigation of Non-Equilibrium Adsorption Character in
Solid Adsorption Refrigeration Cycle, Heat Mass Transfer, Vol. 41, PP. 680-684.
167
Number 7
NOMENCULATUR
b=
=
=
HTF =
Pc=
Pe =
=
=
=
=
=
t cycle =
=
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Journal of Engineering
bed
surface reference diffusivity constant, 2,5*10-4 m2/s
diffusion activation energy, 2.33*106 J/kg
heat transfer fluid
coefficients of the D–A equation = 0.004912 kg/J
adsorption rate constant, m2/s
linear driving force relation constant ( for the Brazilian silica gel = 1)
condensing pressure, kpa
evaporating pressure, kpa
ideal gas constant, 0.462 J/kg.K
radius of adsorbent particle, m
adsorption Temperature, oC
desorption temperature, oC
condensing temperature, oC
evaporating temperature, oC
isosteraing cooling temperature, oC
isosteraing heating temperature, oC
cycle Time, min
adsorbate concentration, kg water/kg adsorbent
maximum adsorption capacity, kg water/kg adsorbent
equilibrium adsorption capacity, kg water/kg adsorbent
difference of adsorbate content, kg water/kg adsorbent
Figue 4. Equilibrium water uptake on silica gel adsorbents at 30oC.
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Adsorption rate constant (m2/s)
Figure 5. Preheating+ desorption/ precooling + adsorption temporal variation with time.
0.040
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0
20
40
60
80
100
Temprature [⁰C]
Figure 6. Adsorption rate constant variation with temperature.
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Figure 7. Adsorption uptake variation with time at constant temperature.
14
12
10
8
6
4
2
Figure 8. Adsorption velocity variation with time (
170
=30oC,
=35oC,
=90oC).
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0.160
Equilibrium, X*, (D-A)
0.140
0.120
Non-equilibrium
X(t)=X*. [1-exp (-k m.t)]
0.100
0.080
0.060
0.040
0.020
0.000
0
20
Time [min]
40
60
Desorption rate (kg water/kg ads.)
Adsorption rate (kg H 2O/kg ads.)
Figure 9. Experimental desorption results variation with time at 90oC hot water.
0.140
0.120
0.100
Non-equilibrium
0.080
0.060
Equlibrium
0.040
0.020
0.000
0
10
20
Time [min]
Figure 10. Comparison between equilibrium and non-equilibrium models.
171
30
40
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Dynamic water sorption,∆X
(kg/kg)
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
0
10
20
30
40
50
Time [min]
Figure 11. Dynamic water sorption.
0.14
0.14
0.12
0.12
0.1
Xdesorption
Xadsorption
0.1
0.08
0.06
0.04
0.08
0.06
0.04
0.02
0.02
0
0
5
10
15
20
0
25
0
10
20
Time [min]
Time[min]
Figure12. Adsorption/Desorption rate variation with time.
172
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0.20
0.16
Pe = 1 kpa
0.14
A
Isosteric
heating
Pc = 4.2 kpa
B
►
0.12
0.10
∆ X= 0.08
X (kg water/kg silica gel)
0.18
0.08
0.06
Isotering
cooling
0.04
◄
D
C
0.02
0.00
10
20
30
40
50
60
70
80
90
100
110
120
130
Bed temperature (°C)
Figure 13. Practical cycles of adsorption and desorption (
173
=90oC,
o
=35
C).
Number 7
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The Effect of Hydraulic Accumulator on the Performance of
Hydraulic System
Dr.Jafar Mehdi Hassan
Prof. Machines and
Equipment . Eng. Dep.
University of Technology
Email- [email protected]
Moayed Waleed Moayed
M.S.c Machines and
Equipment. Eng. Dep.
University of Technology
Email- [email protected]
ABSTRACT
The purpose of this paper is to depict the effect of adding a hydraulic accumulator to a hydraulic
system. The experimental work includes using measuring devices with interface to measure the
pressure and the vibration of the system directly by computer so as to show the effect of accumulator
graphically for real conditions, also the effects of hydraulic accumulator for different applications
have been tested. A simulation analysis of the hydraulic control system using MATLAB.R2010b to
study was made to study the stability of the system depending on the transfer function, to estimate the
effect of adding the accumulator on stability of the system. A physical simulation test was made for
the hydraulic system using MATLAB to show the effect of the accumulator when it's connected to
the system for different parameters and compare it with a PID controller. The hydraulic system has
been simulated and tested using Automation Studio (AS) to measure different data such as the linear
speed of hydraulic cylinder and the effect of connecting the accumulator to the system. All the results
showed that the hydraulic accumulator has a great benefits and a large enhancement to the hydraulic
system.
Keywords: hydraulic system, accumulator, directional valve, relief valve, energy storage
‫تأثٍر مجمع الضغط الهٍذرولٍكً على أداء منظىمه هٍذرولٍكٍه‬
‫د جعفر مهذي حسن‬.‫أ‬
‫مؤٌذ ولٍذ مؤٌذ‬
‫ قعم هىدظة المكائه والمعدات – الجامعه التكىلوجية‬.‫أظتاذ‬
‫قعم هىدظة المكائه والمعدات – الجامعه التكىلوجية‬.‫ماجعتيس‬
‫الخالصة‬
‫ محالةا تحليليةة لىعةاه الةتحكم الميةدزوليكي للمىعومةة‬.‫في هرا البحث تم دزاظةة تةيريس افةافة مجمةظ العلة خلةف ملتلةي الت بياةات‬
‫) لدزاظةةة اظةتاسازاة الىعةةاه أرىةةا العمة اختمةادا خلةةف دالةةة االوتاةا وذلة لتاةةداس تةةيريس‬R2010b .MATLAB) ‫باظةتلداه بسوةةام‬
‫ وقةةةةد تةةةةم خمةةةة محالةةةةا للمكووةةةةات ال يصاائيةةةةة للىعةةةةاه باظةةةةتلداه‬.‫إفةةةةافة مجمةةةةظ الدةةةةل الميةةةةدزوليكي خلةةةةف اظةةةةتاساز الىعةةةةاه‬
‫ إلظماز أرس مجمظ الدل خىدما اكون متصال بما ولعد قيم معتىتجه وماازوتما في حالةة افةافة وحةد تحكةم‬.)MATLAB) ‫بسوام‬
‫ ولةةى ط المىعومةةة التةةي تةةم‬Automation Studio ‫للمىعومةةةت تحلي ة و محالةةا الىعةةاه الميةةدزوليكي باظةةتلداه بسوةةام المحالةةا‬
‫اختبازها خمليا حيث تم بىا ها واختبازها خلف جماش الحاظوب لاياض بياوات ملتل ة مث ظسخة المكبط الميدزوليكي الل ية ودزاظةة‬
‫ وأظمةست الىتةائ أن مجمةظ الدةل الميةدزوليكي لداةه اهميةه فةي تعصاةص وتحعةيه‬.‫تيريس زب مجمظ الدل الميدزوليكي خلف الىعاه‬
. ‫أظتاسااة الىعاه الميدزوليكي‬
.‫ مىعومه هيدزوليكيهت مجمظ فل ت صماه اتجاهيت صماه تى يطت خصان لل اقه‬:‫كلمات رئٍسٍه‬
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1. INTRODUCTION
In the modern world of today, hydraulics plays a very important role in the day-to-day lives of
people. Any device operated by a hydraulic fluid may be called a hydraulic device, but a distinction
has to be made between the devices which utilize the impact or momentum of a moving fluid and
those operated by a thrust on a confined fluid, i.e. by pressure. This leads us to the subsequent
categorization of the field of hydraulics into:
• Hydrodynamics
• Hydrostatics, Ravi 2005.
The most susceptible components in any hydraulic system are the pump, valves, rotary actuators
(motors) or linear actuators (cylinders), reservoirs and connection lines. In addition, some systems
that have a hydraulic accumulator, Arthur 2006. A hydraulic accumulator is a device which stores
pressurized hydraulic fluid. That way, the pump does not have to be powerful enough to cope with a
sudden surge in demand. Instead, it can keep steadily pumping hydraulic fluid and rely on the
accumulator to provide extra hydraulic fluid when it is needed.
Accumulators can perform several functions for hydraulic systems such as:
• Supply oil for high transient flow demands when pump can’t keep up.
• Help to reduce pump ripple and pressure transients.
• Absorb hydraulic shock waves (due to valve closures or actuators hitting stops).
• Used as a primary power source for small (low demand) systems.
• Help system to accommodate thermal
• Compensate for system leakage expansion of the fluid ,Isaiah 2009.
There are three main types of accumulators as shown in Fig .1 bladder, diaphragm bladder
and piston The choice of accumulator to use in a given application depends on required speed
Of accumulator response, weight, reliability and cost.
The bladder accumulator is commonly used in hydraulic systems because of the main advantages of a
bladder accumulator such as, fast acting, no hysteresis, not susceptible to contamination and consistent
behavior under similar conditions. Hence, bladder accumulators are the best choice for pressure
pulsation damping. web1,2012. So we choose this type of accumulator to be used in my experimental
branch test. Yudong X., Y. 2009, presented a dynamic design of electro -hydraulic control valve with
accumulator based on a physical simulation model, he found That velocity oscillation of the electrohydraulic actuator results from the inter coupling effect of the flow pressure pulsation. In order to
reduce the velocity overshoot of the hydraulic actuator, an accumulator can be used to absorb the
pressure pulsations to weaken the inter coupling effect. Xiangdong, k., 2010, presented a simulation
and experimental study on the effects of adding accumulator to the fast forging hydraulic control
system. By using the mathematical model of fast forging system and do simulation study, Minav,T.A
et.al. 2012, presented how to use the hydraulic accumulator as a energy storage device that recovered
from an electro-hydraulic forklift truck. The braking energy can be stored in the hydraulic accumulator
for a long time, and the efficiency of the system increase from 5% to 32%.
2. THEORETICAL MODELING AND SIMULATION
Theoretical model for the main parts of the hydraulic system will be studied, to determine the transfer
function for the system.i-Four-way directional valve controlled cylinder modeling:
The directional valves are one types of the spool valve; the general relations and performance for
the valve have been derived and studied.
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Considering power matching of hydraulic cylinder and directional valve, Fig. 2 shows a schematic
diagram was made using (Auto CAD 2012) of a valve-piston combination. If orifices area of slide
valve is matching and symmetrical as shown in Fig.2, with zero lap, then the flow pressure equation
in the valve is: Herbert, 1967.
1
1
QL  Cd A1 ( PS  PL )  Cd A2 ( PS  PL )
(1)

QS  Cd A1

1
1
( PS  PL )  Cd A2 ( PS  PL )


(2)
Where, the sum of the line pressures (P1) and (P2) is approximately equal to the supply pressure (Ps).
and the same for the supply flow. Valdmier, 2006. Applying the continuity equation to each chamber
of the cylinder yields,
Q1  Cip ( P1  P2 ) 
dV1 V1 dP1

dt
 e dt
C ip ( P1  P2 )  C Ep P2  Q2 
(3)
dV2 V2 dP2

dt  e dt
(4)
The equations above solved simultaneously gives,
(5)
Now by applying Newton's second law to the forces on the piston, the resulting force equation Laplas
transformed, is
Fg  AP PL  M t S 2 X P  BP SX P  KX P  FL
(6)
(7)
Now substitute Eq. (7) into Eq. (5) gives,
*
+
*
*
+
+
The hydraulic natural frequency
176
(8)
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4 e AP
(rad / sec)
Vt M t
2
h 
(9)
And the damping ratio, is
h 
K ce  e M t BP Vt

AP Vt 4 AP  e M t
(10)
Now substitute Eqs. (9) and (10) into Eq. (8) and simplify, the transfer function of the valve
controlled cylinder is given by :
Kq
XP
G v ,c ( s)  X v 
S(
S
2
h
2
AP
2 n

S  1)
(11)
h
3.THE LONG PIPE LINE MODELING
The precise model of fluid transmission pipeline is a dissipative friction model which is related to the
frequency, and it includes a complex Bessel function and a hyperbolic function, as a result, it is very
difficult to get accurate analytical solutions. Therefore, in engineering, the influences of pipeline for
hydraulic system dynamic dynamic behavior are always neglected, which is unfavorable for system
control under the situation of long pipeline. Considering fluid motion feature and physical properties
in pipeline such as mass, damping and pressure, Jiang, 2006. So that the simple mass-springdamping dynamic model can be used to simulate the liquid in pipeline. The model is shown in
Fig.3.
denotes liquid mass,
damping coefficient, (
spring rate,
external force and
displacement. The transfer function model is derived as follows,
(12)
Where, (
is natural frequency of long pipeline,
√
=√
,
) damping ratio,
.
4. PRESSURE RELIEF VALVE MODELING
Fig. 4 shows a schematic diagram was made using, Auto CAD, 2012. of a single-stage pressure
control valves (relief valve). The equations describing spool motion, Herbert, 1967. is,
(13)
And, the linearized continuity equations at the sensed pressure chamber being controlled are
(14)
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(15)
Where,
√ ⁄
= Flow-pressure coefficient of main orifice.
√
√
=
gain of main orifice.
Now, solving Eq. 14 for (
, and substituting into Eq. (15) yields after some manipulation, the
transfer function of pressure control valve (relief valve) is,
(
(16)
)
Where,
Break frequency of sensing chamber.
Break frequency of main volume.
Equivalent flow-pressure
√
Mechanical natural frequency
5. ACCUMULATOR MODELING
According to gas law web1,2012.
(17)
So that
(18)
=
When the state of accumulator changes from condition o to a, Fig.5 the pressure increment is:
(19)
Now for accumulator modeling one can regard accumulator as a gas spring aerodynamic damping
model {9}, and the state can be considered adiabatically, n=1.4. So that the equation of accumulator
is,
̈
̇
̇
(20)
And, the resulting equation Laplas transformed, is
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(21)
(22)
(s)
Now, by combining Eqs. (11), (12), (16) and (22), the Transfer function for the hydraulic system can
be derived:
1- Transfer function for the hydraulic system with accumulator for short pipe.
(
=
(
)
)
(
(23)
)
2- Transfer function for the hydraulic system without accumulator for short pipe
(
=
)
(24)
(
(
)
)
3- Transfer function for the hydraulic system with accumulator for long pipe.
(
)
..
=
(
..
(
)
(25)
)
4- Transfer function for the hydraulic system without accumulator for long pipe.
(
(
)
=
)
(
(26)
)
Fig. 6 shows a simple block diagram of the system.
6. RESULT AND DISCUSSION
The hydraulic accumulator has many benefits to the hydraulic system and some of these benefits
which have been tested experimentally are:
1-The use of accumulator as an storage device energy
Fig.7 represents the time required the hydraulic cylinder to extend for both cases with and without
accumulator and it's clearly shows that the time is decreased when the accumulator is used. The time
required the hydraulic cylinder to extend at system pressure (40 bar) is (2.26 sec), without using the
accumulator and at the same pressure but with connecting the accumulator to the system the time is
(1.72 sec). the decreasing in time required is about (33%).the same result shown at system pressure
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(30, 20 and 10 bar). Fig 8 represents the speed of extending of hydraulic cylinder with pressure for
both cases with and without accumulator, and it clearly shows that the speed increased when the
accumulator connected to the system. This has been happened because the potential energy stored in
accumulator
2- The use of accumulator as a leakage compensator:
The accumulator acts as a compensator, by compensating for losses due to internal or external
leakage that might occur during the operation. Also pressure losses happened due to the friction in
pipes and connections, also due to the increase in oil temperature which affect on the performance of
the hydraulic system. At pump pressures of 40, 30, 20 and10 bars, the decreasing in pressures drop
are about 13.3%, 13 %, 12.7% and 12.5%respestivly ,as shown in Fig.9.
3-The use of accumulator to cushion the vibration of the system:
In this test the effect of adding the accumulator on the vibration of the system have been studied.
Figs. 10 and 11 show the velocity and acceleration of vibration with and without using the
accumulator .At system pressure 40 bar, the velocity and acceleration of vibration is 1.6 mm/sec
and 4.3m/
respectively, So it's clearly that the accumulator cushions the vibration of the system,
also the same results at system pressures (30, 20 and 10 bar). Also a graphical test using vibration
meter with interface software (sw-u801wn) by (lutron company). was made at point before the
relief valve with system pressure 10 bars, Figs. 12 and 13. From the results above it's clearly that the
accumulator reduced the vibration of the system.
4-The use of accumulator as shock absorber:
One of the most important industrial applications of accumulators is in the elimination of highpressure pulsations or hydraulic shocks. Quan, 2007. To test this Phenomena using a graphical chart
display using the pressure meter with interface software (sw-u801 wn) to view the behavior of
pressure at the cylinder when it's suddenly stops at the end of the stroke. The set pressure is 30 bars,
as shown in Fig.14. When the cylinder reached the end of the stroke, the stop without using the
accumulator is suddenly happened and very fast and causes a hydraulic line shock, but with using the
accumulator and from Fig.15. it can be seen that the cylinder stops at the end of the stroke fluently.
So the benefits of adding accumulators to the system are to damp pressure spikes from pumps
.
7. THE SYSTEM STABILITY TEST USING MATLAB PACKAGE V1.1(R2010B):
Fig .16 represents the Bode diagram for the system without connecting the accumulator for
short pipeline, and the result shows that the system is unstable because of the pulsation at the system
response and the over shoot is big. Fig.17 represents the Bode diagram for the system with
connecting the accumulator for the short pipeline, and the result shows that the system is stable with
phase margin of 87.2 deg at frequency of 0.06 rad/sec .Also for a long pipeline Fig.18 represents the
bode diagram for the system without connecting the accumulator and the result shows that the
hydraulic system is unstable. Fig.19 represents the bode diagram for the system with connecting the
accumulator, and the result shows that the system is stable with phase margin of 180 deg. at
frequency of 10.7 rad/sec.
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The physical simulations for the hydraulic system using Matlab V7.11 (R2010b):
A simulation Fig.20 shows the effect of the accumulator when it's connected to the system for
different parameters like cylinder pressure, cyl- inder load, and displacement of cylinder, and the
simulated results are shown in Figs. 21, 22 and 23 respectively. To compare the effect of
accumulator and a PID controller to the system the effect of PID controller are shown in Figs.24, 25
and 25 which makes a self tuner to the system. The self - tuned parameters are found using
MATLAB as P= 0.9, I= 1.2 and D= 0.1. But when we connected the accumulator the system
become more stable and less fluctuation, as shown in Figs. 7, 28 and 29. From the figures above it's
clearly that the accumulator makes the system steadier than the PID controller; for this case.
The Simulation analysis with automation studio package V5.2
The hydraulic system has been built with Automation Studio Package V5.2(AS 2008) to measure
different data, such as the linear speed of hydraulic cylinder and to study the effect of connecting the
accumulator to the system. Figs . 30 and 31. show a compression between the effect of connecting or
disconnecting the accumulator on the linear speed at set pressure of 40 bars. The results of
simulation shows that the liner speed increases by (31%) and the response become much faster. Also
to estimate the effect of using the accumulator as shock absorber, Fig. 32 shows the response of the
cylinder pressure at the end of stroke. It's clearly that the hydraulic cylinder stops suddenly and so
fast which causes a pressure shock at the cylinder, but when the accumulator is connected to the
system the rise of the pressure until the cylinder reached to the end of the stroke become more
smoothly as shown in Fig.33 the set pressure is 10 bar.
8. CONCLUSIONS
The present, theoretical simulation analysis and experimental investigation show several conclusions
these conclusions can be summarized as below:1-The experimental tests showed that the performance of the hydraulic system clearly improvement
by connecting the accumulator to the system and the results showed that the accumulator can be used
in a wide variety of applications such as:
a- Energy storage
b- Leakage compensation
c- Cushion the vibration
d- Emergency operation
e- Shock absorption
It's found that the effect of accumulator as an energy storage is the most common application than
the others.
2- A model equation for the hydraulic system combination has been derived. The theoretical
simulation analysis using the bode diagram showed that the system become stable with connecting
the accumulator.
3- A physical simulation test using Matlab V7.11 (R2010b) was made for the hydraulic system to
show the effect of the accumulator when it's connected to the system for the different parameters, the
results showed that when the accumulator is connected, the system become more stable and less
fluctuation also than the PID Controller, for this case.
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4- The practical results and simulation using (AS) program are clearly convergence. This leads us to
the possibility of using this program for testing and analysis and design of any hydraulic system.
REFERENCES
-Arthur Akers, 2006. Hydraulic System Analysis, Iowa State University Ames, Iowa, U.S.A .
-Automation Studio, 2008. (AS) Automation Studio Circuit Design Simulation Software, Fluid
Power and Automation Technologies. user manual
-Herbert E.Merrit, 1967, Hydraulic Control System, John Wiley and Sons Inc, New York, US, first
edition.
- Isaiah David, 2009, Hydraulic Accumulators Work.
-Jiang Ming, Ming Yali, and Yuan Zhejun, 1999,The Model And Dynamic Characteristics Analysis of Long
Tubes, Journal of Harbin Institute of Technology, vol. 31, no 4, pp. 103-106.
-Minav T.A.,
2012, Storage of Energy Recovered from an Industrial Forklift, LUT Energy, Lappeenranta
University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland.
- Quan Lingxiao, Kong Xiangdong, and Gao Yingjie,2007, Theory And Experimental Research on
Accumulator Absorbing Impulsion without Considering Entrance Characteristics, Chinese Journal of
Mechanical Engineering, 43(9):28-32.
- Ravi Doddannavar and Andries Barnard, 2005, Practical Hydraulic Systems, Linacre House, Jordan Hill,
Oxford.
-Valdmier
M, 2006, Design and Modeling of a New Electro Hydraulic Actuator , National Library of
Canada, M.Sc thesis, Mechanical engineering, Toronto, Canada.
-Xiang dong, 2010, Research of the Influence Factors of the Accumulator Fast Forging Hydraulic Control
System, Heavy Machinery Fluid Power Transmission and Control Key Laboratory of Hebei Yanshan
University Qinhuangdao, China, pp.414-417.
-Yudong Xie, 2009, Dynamic Design of Electro-hydraulic Control Valve Based on Physical Simulation
Model, School of Mechanical Engineering, Shandong University Jinan, China, pp.388-391.
-Web1:2012, Hydraulic Accumulators, Retrieved from Web Site, www. Hydraulic Accumulators.com.
182
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NOMENCLATURE
A1 ,A2
P
PL
:
P1, P2
P
Q1 ,Q2
Qp ideal
Qp actual
QL,Qs
Cd
Cip , Cep
Dp
D
I
Kc
Kce
K1
Kl
N
t
Vt
V 1 , V2
Vc
Vo
Va
Xp
Xv
x
orifice area gradient
piston Surface area
area of accumulator plan
Spool end area
viscous damping coefficient of piston
proportional gain
load
chamber pressure
pressure at system and condition a
pressure of Port A and B
pressure difference
the flow through proportional valve
ideal flow rate of the hydraulic pump
actual flow rate of the hydraulic pump
load and system flow
gas damping factor
discharge coefficient of the valve
internal and external leakage coefficient
volume displacement rate
derivative gain
load force on piston
force generated by piston
integral gain
valve flow gain
equivalent spring rate
gas stiffness factor
spring rate of pipe
valve pressure gain
total flow-pressure coefficient
flow-pressure coefficient of restrictor
leakage coefficient
liquid equivalent mass
total mass of piston
spool mass
rotational speed of pump
time
total hydraulic oil volume in cylinder
forward and return chamber volume
sensing chamber volume
gas volume
volume of accumulator
piston displacement
valve displacement
spool displacement
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GREEK SYMBOLS
Damping coefficient
𝛿
Damping ratio of pipe
184
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Bladder Accumulator
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Journal of Engineering
Piston Accumulator
Figure4. Schematic of a single-stage pressure
relief valve.
Diaphragm Accumulator
Figure 1. The main types of accumulator,
Automation Studio, 2008.
Figure5. Bladder type hydraulic accumulator,
Isaiah David, 2009.
Figure2. Schematic of a valve-piston
combination.
Figure.6 Simple block diagram for the
hydraulic system.
Figure3.Simulation model of liquid in
pipeline, Xiang dong, 2010.
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Figure7. The time required the hydraulic
cylinder to extend for both cases with and
without accumulator.
2014
Journal of Engineering
Figure10. The velocity of vibration for both
cases, with and without connecting the
accumulator.
Figure11. The acceleration of vibration for
both cases, with and without connecting the
accumulator.
Figure8. The speed of extending of hydraulic
cylinder for both cases with and without
accumulator.
Figure12. Acceleration of vibration at set
pressure (10) bar without connecting the
accumulator.
Figure9. The pressure drops across the
hydraulic system.
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Figure13. Acceleration of vibration at set
pressure (10) bar with connecting the
accumulator.
2014
Journal of Engineering
Figure16. The bode diagram for the (tf) of the
hydraulic system without connecting the
accumulator for short pipeline.
Figure17. The bode diagram for the (tf) of the
hydraulic system with connecting the
accumulator for short pipeline.
Figure14. Pressure measured at the cylinder
without connecting the accumulator, the set
pressure is 30bar.
Figure18.The bode diagram for the (tf) of the
hydraulic system without connecting the
accumulator for long pipeline.
Figure15. Pressure measured at the cylinder
with connecting the accumulator.
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Figure19. The bode diagram for the (tf) of the
hydraulic system with connecting the
accumulator for long pipeline.
Figure22. The cylinder load of hydraulic
system without the pid controller or the
accumulator.
Figure20. Physical simulation for the hydraulic
system.
Figure23. The cylinder displacement without
connecting the pid controller or the accumulator.
Figure21. The cylinder pressure of hydraulic
system without the pid controller or the
accumulator.
Figure24. The cylinder pressure of hydraulic
system with connecting the pid controller.
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Figure25.The cylinder load of hydraulic
system with connecting the pid controller.
2014
Journal of Engineering
Figure28. The cylinder displacement of
hydraulic system with connecting the pid
controller.
Figure26. The cylinder displacement of hydraulic
system with connecting the pid controller.
Figure29. The cylinder displacement of hydraulic
system with connecting the accumulator.
Figure27. The cylinder pressure of hydraulic
system with connecting the accumulator.
Figure30. The linear speed and acceleration of
cylinder without connecting the accumulator
using (as).
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Figure31. The linear speed and acceleration of
hydraulic with connecting the accumulator
using (as ).
Figure 33. The cylinder pressure at the end of
stroke with connecting the accumulator using
(as).
Figure32. The cylinder pressure at the end of
stroke without connecting the accumulator
using (as).
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Forward-Reverse Osmosis Processes for Oily Wastewater Treatment
Hasan Farhood Makki
Chemical Engineering Department – College of
Engineering – University of Baghdad – Iraq
[email protected]
Noor Hammood Zghair
Chemical Engineering Department – College of
Engineering – University of Baghdad – Iraq
[email protected]
ABSTRACT
In
this study, the feasibility of Forward–Reverse osmosis processes was
investigated for treating the oily wastewater. The first stage was applied forward osmosis
process to recover pure water from oily wastewater. Sodium chloride (NaCl) and
magnesium chloride (MgCl2) salts were used as draw solutions and the membrane that
was used in forward osmosis (FO) process was cellulose triacetate (CTA) membrane. The
operating parameters studied were: draw solution concentrations (0.25 – 0.75 M), oil
concentration in feed solution (FS) (100-1000 ppm), the temperature of FS and draw
solution (DS) (30 - 45 °C), pH of FS (4-10) and the flow rate of both DS and FS (20 - 60
l/h). It was found that the water flux and oil concentration in FS increase by increasing
the concentration of draw solutions, the flow rate of FS and the temperature for a limit
(40oC), then, the water flux and oil concentration decrease with increasing the
temperature because of happening the internal concentration polarization phenomenon.
By increasing the oil concentration in FS and the flow rate of the DS, the water flux and
oil concentration in FS decreased, while it had a fluctuated behavior with increasing pH
of oily wastewater. It was found also that MgCl2 gives water flux higher than NaCl. So
the values of resistance to solute diffusion within the membrane porous support layer
were 55.93 h/m and 26.21 h/m for NaCl and MgCl2 respectively. The second stage was
applied reverse osmosis process using polyamide (thin film composite (TFC)) membrane
for separating the fresh water from a diluted (NaCl) solution using different parameters
such as draw solution concentration (0.08–0.16 M), feed flow rate (20–40 l/h).
Keywords: membranes separations, forward- reverse osmosis, oily wastewater.
‫العكسي لمعالجة المياه المموثة بالزيوت‬-‫عمميات التنافذ االمامي‬
‫الباحثه نور حمود زغير‬
ٛٗ‫ا‬َٞٞ‫قسٌ اىن‬/ ‫ت اىْٖرست‬ٞ‫ مي‬/‫جاٍعت بغراذ‬
‫ حسن فرهود مكي‬.‫د‬
ٛٗ‫ا‬َٞٞ‫قسٌ اىن‬/ ‫ت اىْٖرست‬ٞ‫ مي‬/‫جاٍعت بغراذ‬
‫الخالصة‬
ٜ‫٘ث فيي‬ٝ‫ييآ اىَي٘ريت بياىط‬َٞ‫ ىَعاىةيت اى‬ٜ‫– اىعنسي‬ٍٜ‫ياث اىخْافيس اامٍييا‬ٞ‫ ٍالئَييت عَي‬ٙ‫ ٕيسٓ اىرشاسيت حييٌ بحيذ ٍير‬ٜ‫في‬
ِ‫٘ث اسيخدرٍج ميو ٍي‬ٝ‫يآ اىَي٘ريت بياىط‬َٞ‫ ٍيِ اى‬ٜ‫ مسيخصجام اىَياق اىْقي‬ٍٜ‫يت اىخْافيس امٍيا‬ٞ‫ طبقيج عَي‬ٚ‫اىَصحيت امٗى‬
ٛ‫ي٘ض حيصا‬ٞ‫ٗاسيخدرً غشياق اىسيي‬
‫و سيح‬ٞ‫( مَحاى‬MgCl2) ً٘ٞ‫س‬ْٞ‫ر اىَغ‬ٝ‫ ٗ مي٘ش‬NaCl ‫ً٘ ا‬ٝ‫ر اىص٘ذ‬ٝ‫اٍالح مي٘ش‬
– 0 25‫ييو اىسييح ا‬ٞ‫ييط ٍحاى‬ٞ‫ حصم‬: ٜ‫ حييٌ ذشاسييخٖا ٕيي‬ٜ‫ت اىخيي‬ٞ‫ي‬ٞ‫اىخشييغ‬
ٗ‫ اىظييص‬ٍٜ‫ييت اىخْافييس امٍييا‬ٞ‫ج خيياله عَي‬ٞ‫خ‬ٞ‫اسيي‬
10 – 4‫ٌ ا‬ٞ‫ت اىيقي‬ٞ‫ُ٘ ذشجيت حاٍضي‬ٞ‫ جيطق بياىَي‬1000 – 100‫ٌ ا‬ٞ‫ ٍحيي٘ه اىقي‬ٜ‫ج ف‬ٝ‫ط اىط‬ٞ‫ ىخص حصم‬/ ‫ٍ٘ه‬0 75
191
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‫ٌ ٍٗحيي٘ه‬ٞ‫ ىنيو ٍيِ ٍحيي٘ه اىيقي‬َٜ‫اُ اىحة‬ٝ‫ ٗ ٍعره اىةص‬oً 45 - 30‫ٌ ٍٗحي٘ه اىسح ا‬ٞ‫ذشجت حصاشة ٍحي٘ه اىيق‬
‫يط‬ٞ‫ حيٌ ذشاسيخٖا اُ ٍعيره حيرفا اىَياق ٗحصم‬ٜ‫ت اىخي‬ٞ‫ي‬ٞ‫اىخشيغ‬
ٗ‫ اىظيص‬ٙ‫ٗجر ضَِ ٍر‬
‫ٌ ٗ ذشجيت اىحيصاشة‬ٞ‫ ىَحيي٘ه اىيقي‬ٜ‫اُ اىحةَي‬ٝ‫ٍعره اىةص‬
‫ط ٍحي٘ه اىسح‬ٞ‫اذة حصم‬ٝ‫طذاذ بط‬ٝ ٌٞ‫ ٍحي٘ه اىيق‬ٜ‫ج ف‬ٝ‫اىط‬
‫اذة ذشجت‬ٝ‫ٌ ٍع ض‬ٞ‫ ٍحي٘ه اىيق‬ٜ‫ج ف‬ٝ‫ط اىط‬ٞ‫قو ٍعره حرفا اىَاق ٗحصم‬ٝ ‫بعر زىل‬
‫ساعت‬/‫ ىخص‬60 - 20‫اىسح ا‬
o
ً 40‫ت ا‬ٝ‫ٌ ٗاىسح ىغا‬ٞ‫و اىيق‬ٞ‫ىَحاى‬
ُ‫يا‬ٝ‫ٌ ٗ ٍعيره اىةص‬ٞ‫ ٍحيي٘ه اىيقي‬ٜ‫يج في‬ٝ‫يط اىط‬ٞ‫ياذة حصم‬ٝ‫ بط‬ٜ‫يط اىيراخي‬ٞ‫اىحصاشة بسب حرٗد ظيإصة اسيخقباا اىخصم‬
‫اذة‬ٝ‫َْا ٗجر اُ ىٔ سي٘ك ٍخسبسا بط‬ٞ‫ٌ ب‬ٞ‫ ٍحي٘ه اىيق‬ٜ‫ج ف‬ٝ‫ط اىط‬ٞ‫قو ٍعره حرفا اىَاق ٗحصم‬ٝ
‫ ىَحي٘ه اىسح‬َٜ‫اىحة‬
‫يير‬ٝ‫ ٍييِ اٍييالح مي٘ش‬ٚ‫ ٍعييره حييرفا ٍيياق اعييي‬ٜ‫ً٘ حعبيي‬ٞ‫سيي‬ْٞ‫يير اىَغ‬ٝ‫ٌ مييسىل ٗجيير بي ُ اٍييالح مي٘ش‬ٞ‫ت اىيقيي‬ٞ‫ذشجييت حاٍضيي‬
26 2 ‫ ً ٗ ا‬/‫ سياعت‬55 9 ‫ت ىيغشياق ا‬ٍٞ‫ٌ اىَقاٍٗيت مّخشياش اىَيساا ذاخيو اىببقيت اىراعَيت اىَسيا‬ٞ‫ً٘ ماّيج قي‬ٝ‫اىص٘ذ‬
‫ييت اىخْافييس‬ٞ‫ييا عَي‬ٞ‫ييت حييٌ حبب‬ّٞ‫ اىَصحيييت اىزا‬ٜ‫ اىخيي٘اى‬ٚ‫ً٘ عييي‬ٞ‫سيي‬ْٞ‫يير اىَغ‬ٝ‫ً٘ ٗ مي٘ش‬ٝ‫يير اىصيي٘ذ‬ٝ‫ ً ىنييو ٍييِ مي٘ش‬/‫سيياعت‬
‫يط ٍحيي٘ه اىسيح‬ٞ‫يصاث ٍدخيفيت مخصم‬ٞ‫ً٘ اىَدفف باسيخدراً ٍخغ‬ٝ‫ر اىص٘ذ‬ٝ‫ ٍِ ٍحي٘ه مي٘ش‬ٜ‫ ىفصو اىَاق اىْق‬ٜ‫اىعنس‬
‫ساعت‬/‫ ىخص‬40- 20‫ ىَحي٘ه اىسح ا‬َٜ‫اُ اىحة‬ٝ‫ ىخص ٍٗعره اىةص‬/ ‫ٍ٘ه‬0 16 – 0 08‫ا‬
1.INTRODUCTION
One of the most challenging problems today is the removal of oil from wastewater.
Large amounts of wastewater are generated by industrial companies that produce or
handle oil and other organic compounds, both immiscible and miscible in water. Oily
wastewater discharged into the environment causes serious pollution problems since the
biodegradability of oil is very low and oily wastewater hinders biological processing at
sewage treatment plants , Mohammed et al., 2011. Oily wastewater is defined as liquid
waste either from automotive workshop or oil industry and known as a combination of
water with some surface oil, oil sludge or sediments which contained lubricants, cutting
fluid and heavy hydrocarbon such as tars, grease and diesel oil, bacteria and light
hydrocarbon at concentration that may vary from a few hundred parts per million to as
much as 1 to 10 percent by volume , Bujang et al., 2012. Oil and grease in wastewater
can exist in several forms: free, dispersed or emulsified. The differences are based
primarily on size ,Cheryan and Rajagopalan, 1998. Based on the form of the oil in the
water, different methods have been applied to its removal. Conventional oily wastewater
treatment methods include gravity separation and skimming, dissolved air flotation, deemulsification, coagulation and flocculation, which have several disadvantages such as
low efficiency, high operation costs, corrosion and recontamination problems ,Yan et al.,
2006. Osmosis a physical phenomenon extensively studied by scientists in various
disciplines of science and engineering. In a FO process, water diffuses spontaneously
through a semi-permeable membrane from a feed solution (FS) with low osmotic
pressure to a draw solution (DS) with high osmotic pressure , Zhao and Zou, 2011. The
osmotic driving forces in FO can be significantly greater than hydraulic driving forces in
RO, theoretically, leading to higher water flux rates and recoveries. Besides low or no
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hydraulic pressure requirements for FO process, high rejection of a wide range of
contaminants, lower membrane fouling, and simplicity of equipment used in the process
are additional advantages of FO ,Bamaga et al., 2011 and Kim et al., 2012.
In 1886, van't Hoff formulated an equation to calculate osmotic pressure (π), based on
data for sugar solution and the similarity of dilute solutions to ideal gases ,Thain, 1967.
(1)
where C is the concentration of solute, T is the temperature of solution, Rg is the gas
constant, i is number of dissociated ions per molecule, and
is osmotic coefficient.
Basically, the FO desalination process involves two steps. In the first step, the fresh water
is extracted from the raw water source using a suitable draw solution (osmotic agent
having a high osmotic pressure). The second step deals with separation of the osmotic
agent from the fresh water , Bamaga et al., 2011. The diluted draw solution that was
produced from FO process is subsequently desalinated by RO to produce fresh water
suitable for beneficial uses , Xie et al., 2012.
The main goal in this study was to investigate the technical feasibility and the
efficiency of FO– RO processes for treating the oily wastewater. The first stage is
application forward osmosis process to recovery of water from oily wastewater using FO
process. In the second stage, a technically reverse osmosis process was employed to treat
the diluted draw solution outlet from forward osmosis using polyamide and the effect of
(NaCl) concentration in feed solution and feed flow rate were studied on water flux for
RO process.
2.CONCENTRATION POLARIZATION
Concentration polarization is the term used to describe the accumulation of rejected
solute at the surface of a membrane so that the solute concentration at the membrane wall
is much higher than that of the bulk feed solution , Ahmed, 2007. Because asymmetric
FO membranes are comprised of a dense layer on top of a porous support layer,
concentration polarization occurs externally at the feed–membrane and draw solution–
membrane interfaces, and internally in the porous support layer of the membrane ,Achilli
et al., 2010. Below, these two concentration polarization phenomena are quantitatively
described.
2.1 External Concentration Polarization
In osmotic processes, concentration polarization can occur on both sides of the
membrane. Concentrative external concentration polarization occurs in forward osmosis
when the feed solution is placed against the active layer of the membrane. To account for
this phenomenon, the extent of concentration polarization was calculated from film
theory. The concentrative external concentration polarization moduli at each permeate
flux, Jw, could be calculated using ,Ahmed, 2011.
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( )
Where, Jw is the experimental permeate water flux, k is the mass transfer coefficient and
πF,m and πF,b are the osmotic pressures of the feed solution at the membrane surface and in
the bulk, respectively. Note that the exponent is positive, indicating that πF,m > πF,b
(McCutcheon and Elimelech, 2006). The mass transfer coefficient, k, is:
(3)
Where, Sh is Sherwood number, D is the solute diffusion coefficient and dh is hydraulic
diameter.
Simultaneously, the draw solution in contact with the permeate side of the membrane is
being diluted at the permeate-membrane interface by the permeating water. This is called
dilutive ECP , Digman, 2010. Dilutive external concentration polarization can be
calculated also from film theory. The external concentration polarization modulus
(πD,m/πD,b) is calculated using:
(
)
where πD,m is the osmotic pressure at the membrane surface and πD,b is the bulk osmotic
pressure of the draw solution. JW is negative in this equation because the water flux is in
the direction of the more concentrated solution and the concentration polarization effect
is dilutive (πD,m< πD,b). To model the flux performance of the forward osmosis process in
the presence of external concentration polarization, we start with the flux equation for
forward osmosis, given as ,Achilli et al., 2009.
(5)
Here, A is the pure water permeability coefficient, σ is the osmotic reflection
coefficient, has a value of 1. Eq. (5) predicts flux as functions of driving force only in the
absence of concentrative or dilutive ECP, which may be valid only if the permeate flux is
very low. When flux rates are higher, this equation must be modified to include both the
concentrative and dilutive ECP , McCutcheon and Elimelech, 2006.
*
(
)
( )+
(6)
2.2 Internal Concentration Polarization
Internal concentration polarization (ICP) is closely related to external concentration
polarization (ECP) at the surface of the active layer as shown in Fig. 1 ,Alsvik and
Hägg, 2013. The ICP phenomenon occurs on the permeate side. We refer to this as
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dilutive ICP since the draw solution is diluted by the permeate water within the porous
support of the membrane ,McCutcheon and Elimelech, 2006. Loeb et al., 1997.
similarly described flux behavior in the FO mode ,Cath et al., 2006.
( )
(7)
where K is the resistance to solute diffusion within the membrane porous support layer
which is a measure of how easily a solute can diffuse into and out of the support layer
and thus is a measure of the severity of ICP, is defined as:
(8)
where t is the membrane thickness, τ is the tortuously of the membrane porous support
layer, ε is porosity of the porous support layer, and D is the diffusion coefficient of the
solute. Because t, τ, and ε are fixed for our FO membrane, K is dependent only on D
,Gray et al., 2006.
When assuming that B = 0, σ = 0 (i.e., the salt permeability is negligible) and the
equation (7) is rearranged, an implicit equation for the permeate water flux is obtained:
[
]
(9)
Here, πD,b is now corrected by the dilutive ICP modulus, given by:
(10)
where πD,i is the osmotic pressure of the draw solution on the inside of the active layer
within the porous support. The negative exponent is indicative of dilution at this point, or
πD,i < πD,b .
By substituting Eq. (2) into (9) ,Cath et al., 2006.
*
( )+
(11)
In this study assuming that the salt permeability coefficient (B) is equal to zero
and the small value of the flux (JW) compared to osmotic pressure of draw solution,
therefore the Equations (8) it can simplify as follows:
(
)
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Journal of Engineering
Figure 1: Concentration polarization in an asymmetric membrane in FO (concentrative
ECP and dilutive ICP) ,Achilli et al., 2010.
3. MATERIALS AND METHODS
3.1 The membranes
An asymmetric FO membrane acquired from Hydration Technology Innovations (XPackTM supplied by Hydration Technology Inc., Albany, OR) was used for forward
osmosis experiments in this study. The membrane that was used is a cellulose triacetate
casted onto a non-woven back support consisting of polyester fibers individually coated
with polyethylene. The physical characteristics of this specific CTA membrane are
unique compared with other commercially available semi-permeable membranes and has
been acknowledged to be the best available membrane for most FO applications ,Choi,
2011. The CTA membrane lacks a thick support layer with thickness of the membrane is
less than 50 µm and membrane salt rejection is (95-99 %). While a thin film composite
membrane (TFC) was used in RO process. TFC membrane is an aromatic polyamide
consisting of three layers: polyester support web (120 μm), micro porous poly sulphone
interlayer (40 μm), and ultra thin polyamide barrier layer on the top surface (0.2 μm). The
specifications of the TFC membrane are salt rejection (96 – 99 %), maximum operating
pressure (6 – 9 Mpa), maximum operating temperature 45 oC and pH range for
continuous operation (2 – 11).
3.2 Feed and draw solutions preparation
Gasoline and diesel engine oil was used for preparation of the O/W emulsion with total
volume was 5 liters. The O/W emulsion was prepared by vigorous mixing of oil and
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deionized water using a stirrer at an agitation speed of 2000 rpm for 15 min. The
concentrations of oil that was prepared for the feed solution were 100, 500 and 1000
ppm. The phycical specifications of the oil are given in Table 1. Whereas two types of
salts (NaCl and MgCl2) were used for preparing the draw solutions in FO experiments.
The concentrated draw solution was made by dissolving a solid salt in deionized water
with concentrations of 0.25, 0.5, and 0.75 M. The chemical analysis of the salts (NaCl
and MgCl2) is given in Table 2. The total draw solution volume was 5 liters. These
chemicals were chosen in preparation of draw solutions for their relatively low molecular
weight, high solubility, high osmotic pressure that can be given by this solution, easily
and economically separated and recycled, and previous interest or utilization in FO
research.
Table 1.Typical physical characteristics of oil (Shell Helix HX5).
Viscosity grade
15W-40
Kinematic viscosity (40 °C) 105.4 c St
Kinematic viscosity (100 °C) 13.9 c St
Viscosity index
132
Density at 15 °C
0.885 kg/l
Flash point PMCC
220 °C
Pour point
-30 °C
Table 2.Chemical Specifications of Draw Solutions
Assay 99.5% min.
Max. limits of
Sodium
Chloride impurities (%)
(NaCl)
Ammonia 0.002
MW = 58.44
Iron
0.002
Lead
0.0005
Potassium 0.02
Sulphate
0.02
Assay 98% min.
Max. limits of
Magnesium
impurities (%)
Chloride (MgCl2)
Sulfate
0.002
MW = 95
Copper
0.002
Lead
0.005
Iron
0.0005
Zinc
0.0005
Cadmium 0.005
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4. EXPERIMENTAL SYSTEMS
4.1 Forward Osmosis System
Experiments were conducted using a laboratory-scale FO system consists of two
cylindrical QVF glass vessels with a capacity of 7 liters were used as a feed and draw
solutions vessels, two centrifugal pumps were used to pump the feed and draw solutions
from vessels to high pressure pumps. Each with flow rate rang of 11.4-54.6 L/min, a head
of 3-13.7 m. Then, the draw solution and feed solution that supplied from centrifugal
pumps were pumped using high pressure pumps 125 psi (MAX PRESSURE)) to forward
osmosis cell. The forward osmosis cell was circular plate and frame membrane cell and it
consisted of two semi-cells which were made of Teflon. It was designed with two flow
channels and the diameter of each circular channel was 12.5 cm with a depth of 3 cm in
draw solution side and 4 cm in the feed side whereas the total effective for CTA
membrane area was 165 cm2. To measure the volumetric flow rate of feed and draw
solutions, two calibrated rotameters were used each of ranged (10 - 60 l/hr). While two
submersible electrical coils (220 Volt, 1000 Watt) and thermostats of range (0- 80oC)
were used to control temperatures on the solutions. The pH of FS was adjusted to the
required value by addition of (NaOH) or (HCl) and the acidity of O/W emulsion was
measured using pH meter (Model 2906, Jenway Ltd, UK) and a pH probe. Digital
laboratory conductivity meter was used to measure the concentration of the draw
solution, range (0-2 × 106 µs/cm), operating temperature (0-55 °C), accuracy (± 0.5 %
Full Scale), also the concentration of oil in water was measured using spectrophotometer
(Genesys 10 UV, Wave length = 1090 – 190 nm).
4.2 Experimental Procedure
In the typical orientation of forward osmosis process, the draw solution was
placed against the support layer and the feed solution was on the active layer. The feed
and draw solutions were operated in a counter-current flow configuration (feed and draw
solution flowing tangential to the membrane but in opposite directions). This mode of
operation provides constant ∆π along the membrane module and makes the process more
efficient. The outlet streams of feed and draw solutions were recycled back to the main
vessels. All experiments were carried out with applying a pressure of 0.5 bar across the
membrane sheet in the feed side. The time of experiment was five hours. For every one
hour, water flux into the DS was calculated. Also oil concentration in FS was measured.
Fig. 2 shows the schematic diagram of forward osmosis system.
For cleaning the membrane, osmotic backwashing was made in order to remove oil
droptets that accumulated on or in the pores of the membrane. In the backwashing process, the
direction of water permeation across the semipermeable membrane was reversed and the DS was
replaced with a deionized water and FS was replaced with 0.5 M of a brine. So the same pressure
was applied in the permeate side. Dionized water flows through draw side channel, the osmotic
pressure gradients are formed in an opposite direction and permeate (i.e. backwash water) flows
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from draw side (dionized water) to feed side (brine). Therefore, foulants on the membrane surface
are detached by this opposite flow and then are removed from the membrane surface.
4.3 Reverse Osmosis System
For recovery of pure water, the diluted draw solution was treated using reverse
osmosis unit that was run in a closed loop. QVF glass vessel with a capacity of 30 liters
was used as a feed solution vessel and high pressure pump was used to pump the feed
solution (or diluted draw solution) from the QVF vessel to spiral wound module. The
spiral – wound element are adopted and operated with only one stream (the feed stream)
flowing under direct control of its flow velocity tangential to the membrane, (membrane
type is thin film composite (TFC), membrane length is 115 cm, membrane width is 21cm,
diameter is 3 in., number of membrane is 2 and membrane active area is 4830 cm2.
The feed solution in RO process was prepared by dissolving the solid salt (NaCl)
in 15 liters of deionized water and was placed in the QVF glass vessel. Pressure gauge
measured the pressure that was maintained 9 bars at the inlet module. Then the feed inter
the spiral wound module in order to separate draw solution into two streams; one
contained pure water and the other contained concentrated solution that was recycled to
main feed vessel. The time of experiment was 2 hr, so for every a quarter hour, the water
flux was calculated. An experimental rig of reverse osmosis unit was constructed in the
laboratory as shown schematically in Fig. 3.
Figure 2. The schematic diagram of the laboratory scale forward osmosis membrane
apparatus.
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Figure 3.Schematic diagram of spiral-wound reverse osmosis process.
5. Results and discussion
5.1 Forward Osmosis
5.1.1 Effect of Draw Solution Concentration
The effect of draw solution concentration of (NaCl) and (MgCl2) on water flux is shown
in Figures 4 and 5. When the concentration of draw solution increased, the water
permeation across the membrane increased, as a result, the water flux increased. This is
expected and attributed to the increasing in the osmotic pressure difference across the
membrane with an increase in the concentration of draw solution, which results in an
increase in the driving force) for water transport through the membrane. Also with
increasing of draw solution concentration, the concentration of O/W emulsion increases
because of the increasing in water transport across the membrane as in Fig.s 6 and 7.
From Figs. 4, 5, 6 and 7. it can be seen that the flux of water and oil concentration using MgCl2
solution as draw solution were greater than that using NaCl solution because it has osmotic
pressure higher than the osmotic pressure for NaCl and the osmotic pressure depends on the
number of dissociates and osmotic coefficient of the solute (as in Eq (1)).
5.1.2 Effect of Oil Concentration in Feed Solution
Generally, the higher concentration of oil in feed is the lower amount of the permeate
flux as observed in Figures 8 and 9. When the concentration increased from 100 to 1000
ppm, the adsorption of oil droplets increased and formed an accumulated layer of oil on
the membrane surface (active layer). This causes easily great resistance for permeating
water across the membrane and this layer cannot be removed by hydrodynamic action of
flow. While at lower concentrations, the accumulation oil on the membrane surface was
lower and can be removed by hydrodynamic action of flow. So the increase of oil
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concentration was increased the osmotic pressure of feed solution and decrease of driving
force (∆π) as shown in van't Hoff equation. The O/W emulsion lost quantities of pure
water and this increased concentration of the oil in emulsion as in Figs .10 and 11.
5.1.3 Effect of Temperature
When the temperature increased from 30 to 40°C, the water permeation increased
through the membrane. As a result, the water flux and the concentration of oil in the feed
solution increased with this range of temperature as observed in Fig’s (12, 13, 14 and
15). The increase in temperature of both feed and draw solutions reduces the viscosity of
solutions and increases the diffusion rate of water through the membrane leading to lower
resistance against passage of flow, which results the increasing in the volume of water
that passed into the draw solution. Additionally, thermal expansion of active layer of the
membrane could also be a reason for an increase in the permeate flux with increasing
temperature , Alturki, 2013.
Also according to van't Hoff equation, increasing in the temperature can be
increased the osmotic pressure of a salt solution. The water flux decreased when the
temperature of oil/water emulsion and draw solution were rose from 40 to 45°C. This
means that the increasing in temperature from 40 to 45°C accounted for a fall in effective
osmotic pressure difference inside the membrane as an inherent result of higher internal
concentration polarization or may be attributed for specifications of the oil that was used.
The results obtained here are in good agreement with , Aydiner et al., 2012.
5.1.4 Effect of Feed Solution pH
The performance of FO process was highly dependent on the pH of O/W emulsion so it
was affected not only by the characteristics of membrane but also by the performance of
the solute (droplet). Figs. 16 and 17 indicated that the flux increased sharply with
increase the pH from 4 to 7.3, then reduced with the increase of pH from 7.3 to 10. In
general, the flux under various pH values was affected by the properties of the solute (oil
droplets) especially zeta potential of the emulsion.
The coagulation of emulsion droplets on membrane happened under low values of
pH (i.e. pH = 4) as the zeta potential of emulsion droplet was low in absolute value and
this led to decrease the inter-droplet repulsion. Therefore, the lower level of flux was
observed at low pH. While the emulsion droplets had the higher negative charge at higher
pH values. The oil layer became more “open” at high pH due to the inter-droplet
repulsion, and this increased the permeability, resulting in higher permeate flux.
Meanwhile, the inter-droplet repulsion prevented the particle from depositing, and led to
the reduction of the thickness of cake layer. The results obtained here are in good
agreement with ,Hua et al., 2007. So the oil concentration in the feed solution also
fluctuates with increasing the pH of the emulsion according to the fluctuation of water
flux in the same manner as shown in Figs. 18 and 19.
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5.1.5 Effect of Draw Solution Flow Rate
Figs. 20 and 21 show the effect of draw solution flow rate on water flux with time for
NaCl and MgCl2 respectively. Increasing the draw solution flow rate from 20 to 60 l/hr
increased the extent of hydrodynamic mixing and prevented the concentration buildup in
the solution at the vicinity of the membrane surface (support layer), and resulting in
decrease the driving force. Thus, water flux decreased with increasing draw solution flow
rate. As observed in Figs. 22 and 23, the oil concentration in feed solution decreased also
with increasing the flow rate of draw solution due to this decreasing in water transport
across the membrane with this range of draw solution flow rate.
5.1.6 Effect of Feed Solution Flow Rate
Figs. 24 and 25 present the effect of feed solution flow rate on the FO process efficiency.
The water flux increased with increasing the feed solution flow rate. The increase in the
feed solution flow rate near the membrane surface increases the extent of hydrodynamic
mixing and increases Reynolds number and this enhances turbulence over the active layer
of the membrane. As a result, it increases mass transfer coefficient in the concentration
boundary layer and this can reduce accumulation of the oil droplets (i.e reducing the
external concentration polarization). Therefore, the oil droplets on the membrane surface
diffuse back to the bulk solution and this causes increase water permeation across the
membrane. The oil concentration in feed solution increased as a result of the increasing
transmission of water from feed solution through the membrane as shown in Figs. 26 and
27.
5.1.7 The Analysis of Concentration Polarization
In Figs. 28 and 29, the water flux (JW) is presented as a function of logarithm of the ratio
of draw and feed solutions osmotic pressures (ln(πD/πF)) (Equ. (12)). It was found that the
slope of line represents the inverse of the solute resistivity for diffusion within the porous
support layer (K). K can be used to determine the influence of internal concentration
polarization on water flux and to describe how easily solute can diffuse in and out of the
support layer. Osmotic pressure was calculated according to the Eq. (1), where numbers
of dissociated ions for NaCl, MgCl2 and oil are (i = 2, 3, 1) respectively and the osmotic
coefficient for ideal solution is (Φ = 1). The value of (K) for NaCl was found 55.93 h/m,
while its value for MgCl2 was equal to 26.21 h/m. This is meaning that NaCl
(monovalent) diffused through the membrane more rapidly than the MgCl2 (divalent)
because of its relatively small hydration radius. Therefore the influence of internal
concentration polarization on water flux for NaCl solution was higher than for MgCl2
solution.
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6. REVERSE OSMOSIS
6.1 The Effect of NaCl Concentration
The influence of NaCl feed concentration on water flux is shown in Figure 30.
According to the results, the lower salt concentration is the higher permeation flux of the
membrane. These results are attributed to the increasing in osmotic pressure with
increasing the NaCl concentration and formation of a salt layer on the membrane surface
with thickness increases with increasing feed concentration.
6.2 Effect of Feed Flow Rate
Fig31. shows the effect of feed flow rate on the water permeate flux of diluted NaCl draw
solution. As shown increasing flow rate from 20 to 40 l/h leads to increase permeate flux
rate. This behavior may be attributed to the fact that increasing cross flow velocity leads
to the increase of turbulence and mass transfer coefficient. This weakens the effect of
concentration polarization and reduces accumulate of the salt which essentially acts as a
dynamic membrane, as a result the salt on the membrane surface diffuse back to the bulk
solution and increases the permeate flux. The results obtained here are in good agreement
with ,Shamel and Chung , 2006).
10
7
8
5
J (l/m2. h)
J (l/m2. h)
6
4
3
Cd =0.25 M
2
1
0
0
6
Cd = 0.5 M
2
Cd = 0.75 M
0
2
Time (h)
4
Cd =0.25 M
4
Cd = 0.5 M
Cd = 0.75 M
0
6
2
4
6
Time (h)
Figure 5. Water flux J (l/m2.h) with time
at different concentration of DS for
MgCl2 (Coil= 500 ppm, Temp. of FS &
DS = 30 °C and pH of FS = 7.3, Qd = 50
l/h, Qf = 60 l/h, P = 0.5 bar).
Figure 4.Water flux J (l/m2.h) with time
at different concentration of DS for NaCl
(Coil= 500 ppm,Temp. of FS & DS = 30
°C and pH of FS = 7.3, Qd = 50 l/h, Qf =
60 l/h, P = 0.5 bar).
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10
8
J (l/m2. h)
Coil
(ppm)
540
535
530
525
520
515
510
505
500
20
Cd =0.25 M
Cd = 0.5 M
Cd = 0.75 M
0
2
6
4
Cf = 100 ppm
Cf = 500 ppm
Cf = 1000 ppm
2
0
4
0
6
2
1200
Cd =0.25 M
Cd = 0.5 M
Cd = 0.75 M
1000
Coil
(ppm)
Coil
(ppm)
6
Figure 9. Water flux J (l/m2.h) with time at
different oil concentration of FS for MgCl2
(Cd = 0.5 M, Temp. of FS & DS = 30 °C and
pH of FS= 7.3, Qd = 60 l/h, Qf = 60 l/h, p =
0.5 bar).
Figure 6. The oil concentration Coil (ppm) in
FS with time at different concentration of
DS for NaCl (Coil= 500 ppm, Temp. of FS &
DS = 30 °C and pH of FS = 7.3, Qd = 50 l/h,
Qf = 60 l/h, P = 0.5 bar).
550
545
540
535
530
525
520
515
510
505
4
Time (h)
Time (h)
Cf = 100 ppm
Cf = 500 ppm
Cf = 1000 ppm
800
600
400
200
0
2
4
0
6
0
2
4
6
Time (hr)
Time (h)
Figure 7. The oil concentration Coil (ppm) in
FS with time at different concentration of
DS for MgCl2 (Coil= 500 ppm, Temp. of FS
& DS = 30 °C and pH of FS = 7.3, Qd = 50
l/h, Qf = 60 l/h, P = 0.5 bar).
Figure 10:. The oil concentration Coil (ppm)
in FS with time at different oil concentration
in FS for NaCl (Cd = 0.5 M, Temp. of FS &
DS = 30 °C and pH of FS= 7.3, Qd = 60 l/h,
Qf = 60 l/h, p = 0.5 bar).
1000
Coil
(ppm)
J (l/m2. hr)
1200
7
6
5
4
3
2
1
0
Cf = 100 ppm
Cf = 500 ppm
Cf = 1000 ppm
0
2
Cf = 100 ppm
800
Cf = 500 ppm
600
Cf = 1000 ppm
400
200
4
0
6
0
Time (hr)
2
4
6
Time (h)
Figure 8.Water flux J (l/m2.h) with time at
different oil concentration of FS for NaCl
(Cd = 0.5 M, Temp. of FS & DS = 30 °C and
pH of FS= 7.3, Qd = 60 l/h, Qf = 60 l/h, p =
0.5 bar).
Figure 11. The oil concentration Coil (ppm)
with time at different oil concentrati Figure
on in FS for MgCl2 (Cd = 0.5 M, Temp. of
FS & DS = 30 °C and pH of FS= 7.3, Qd =
60 l/h, Qf = 60 l/h, P = 0.5 bar).
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8
550
6
540
545
535
Coil
(ppm)
J (l/m2.h)
Number 7
T =30°C
4
530
T = 35°C
2
0
T = 40°C
520
T = 45°C
515
0
T = 30°C
T = 35°C
T = 40°C
T = 45°C
525
2
4
510
6
0
Time (h)
Figure 12. Water flux J (l/m2.h) with time at
different Temp. of FS & DS for NaCl (Cd =
0.5 M, Coil= 500 ppm and pH of FS = 7.3,
Qd = 60 l/h, Qf = 60 l/h, P = 0.5 bar).
2
Time (h)
4
6
Figure 15.The oil concentration Coil (ppm)
with time at different Temp. of FS & DS for
MgCl2 (Cd = 0.5 M, Coil= 500 ppm and pH
of FS = 7.3, Qd = 60 l/h, Qf = 60 l/h, P = 0.5
bar).
6
8
5
6
J (l/m2. h)
J (l/m2.h)
10
T =30°C
T = 35°C
T = 40°C
T = 45°C
4
2
4
3
PH = 4
2
0
PH= 7.3
1
0
2
4
6
PH= 10
0
Time (h)
0
2
4
6
Time (h)
2
Figure 13. Water flux J (l/m .h) with time at
different Temp. of FS & FS for MgCl2 (Cd =
0.5 M, Coil= 500 ppm and pH of FS = 7.3,
Qd = 60 l/h, Qf = 60 l/h, P = 0.5 bar).
Figure 16. Water flux J (l/m2.h) with time at
different pH of FS for NaCl (Cd = 0.5 M,
Coil= 500 ppm and Temp. of FS & DS = 30
°C, Qd = 60 l/h, Qf = 60 l/h, P = 0.5 bar).
540
8
525
J (l/m2. h)
Coil
(ppm)
535
530
T = 30°C
T = 35°C
T = 40°C
T = 45°C
520
515
510
505
0
2
4
6
4
PH = 4
PH= 7.3
PH= 10
2
6
0
Time (h)
0
2
4
6
Time (h)
Figure 14. The oil concentration Coil (ppm)
in FS with time at different Temp. of FS &
DS for NaCl (Cd = 0.5 M, Coil= 500 ppm and
pH of FS = 7.3, Qd = 60 l/h, Qf = 60 l/h, P =
0.5 bar).
Figure 17. Water flux J (l/m2.h) with time at
different pH of FS for MgCl2 (Cd = 0.5 M,
Coil= 500 ppm and Temp. of FS & DS = 30
°C, Qd = 60 l/h, Qf = 60 l/h, P = 0.5 bar).
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535
8
J (l/m2. h)
Coil
(ppm)
530
525
520
515
PH = 4
PH = 7.3
PH = 10
510
505
6
Qd = 20 l/h
Qd = 40 l/h
Qd = 60 l/h
4
2
0
500
0
2
Time(h)
4
0
6
540
535
530
525
520
515
510
505
530
Coil
(ppm)
525
PH = 4
PH = 7.3
PH = 10
2
4
520
Qd = 20 l/h
515
Qd = 40 l/h
510
Qd = 60 l/h
505
6
0
Figure 19. The oil concentration Coil (ppm)
with time at different pH of FS for MgCl2
(Cd = 0.5 M, Coil= 500 ppm and Temp. of FS
& DS = 30 °C, Qd = 60 l/h, Qf = 60 l/h, P =
0.5 bar).
Coil
(ppm)
5
Qd = 20 l/h
Qd = 40 l/h
Qd = 60 l/h
1
2
4
2
Time (h)
4
6
Figure 22.The oil concentration Coil (ppm)
in FS with time at different draw solution
flow rate (Qd) for NaCl (Cd = 0.5 M, Coil=
500 ppm, Temp. of FS & DS = 30 °C, pH of
FS = 7.3, Qf = 60 l/h, P = 0.5 bar).
7
J (l/m2. h)
6
Figure 21. Water flux J (l/m2.h) at different
time at different draw solution flow rate (Qd)
for MgCl2 (Cd = 0.5 M, Coil= 500 ppm,
Temp. of FS & DS = 30 °C, pH of FS = 7.3,
Qf = 60 l/h, P = 0.5 bar).
Time(h)
0
4
535
0
3
2
Time (h)
Figure 18.The oil concentration Coil (ppm)
with time at different pH of FS for NaCl (Cd
= 0.5 M, Coil= 500 ppm and Temp. of FS &
DS = 30 °C, Qd = 60 l/h, Qf = 60 l/h, P = 0.5
bar).
Coil
(ppm)
Journal of Engineering
6
550
545
540
535
530
525
520
515
510
Qd = 20 l/h
Qd = 40 l/h
Qd = 60 l/h
0
Time (h)
2
4
6
Time(h)
Figure 23.The oil concentration Coil (ppm)
in FS with time at different draw solution
flow rate (Qd) for MgCl2 (Cd = 0.5 M, Coil=
500 ppm, Temp. of FS & DS = 30 °C, pH of
FS = 7.3, Qf = 60 l/h, P = 0.5 bar).
Figure 20. Water flux J (l/m2.h) with time at
different draw solution flow rate (Qd) for
NaCl (Cd = 0.5 M, Coil= 500 ppm and Temp.
of FS & DS = 30 °C, pH of FS = 7.3, Qf =
60 l/h, P = 0.5 bar).
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540
6
Coil
(ppm)
J (l/m2. h)
535
4
Qf = 20 l/h
Qf = 40 l/h
Qf = 60 l/h
2
525
520
Qf = 40 l/h
510
2
4
Qf = 60 l/h
505
6
0
Time (h)
2
8
6
4
6
y = 17.884x - 118.28
J (l/m2. h)
6
4
Qf = 20 l/h
Qf = 40 l/h
Qf = 60 l/h
2
0
2
4
4
2
6.800
0
6
6.850
ln(πNaCl/πoil)
Time (h)
Figure 25.Water flux J (l/m2.h) with time at
different feed solution flow rate (Qf) for
MgCl2 (Cd = 0.5 M, Coil= 500 ppm, Temp.
of FS & DS = 30 °C, pH of FS = 7.3, Qd =
60 l/h, P = 0.5 bar).
535
8
530
7
525
520
Qf = 20 l/h
515
2
4
5
3
7.180
Qf = 60 l/h
505
0
6
y = 38.154x - 270.19
4
Qf = 40 l/h
510
6.900
Figure 28. Water flux against the logarithm
of the ratio of osmotic pressures for
calculate K (Cd = 0.5 M, Cf = 500 ppm,
Temp. of FS & DS = 30oC, pH = 7.3, Qd =
60 l/h, Qf = 60 l/h, and P= 0.5 bar).
J (l/m2. h)
Coil
(ppm)
Time (h)
Figure 27. The oil concentration Coil (ppm)
in FS with time at different feed solution
flow rate (Qf) for MgCl2 (Cd = 0.5 M, Coil=
500 ppm, Temp. of FS & DS = 30 °C, pH of
FS = 7.3, Qd = 60 l/h, P = 0.5 bar).
Figure 24. Water flux J (l/m2.h) with time at
different feed solution flow rate (Qf) for
NaCl (Cd = 0.5 M, Coil= 500 ppm, Temp. of
FS & DS = 30 °C, pH of FS = 7.3, Qd = 60
l/h, P = 0.5 bar).
J (l/m2.h)
Qf = 20 l/h
515
0
0
530
6
7.200
7.220
7.240
7.260
7.280
7.300
ln(πMgCl2/πoil)
Time (h)
Figure 26.The oil concentration Coil (ppm)
in FS with time at different feed solution
flow rate (Qf) for NaCl (Cd = 0.5 M, Coil=
500 ppm, Temp. of FS & DS = 30 °C, pH of
FS = 7.3, Qd = 60 l/h, P = 0.5 bar).
Figure 29. Water flux against the logarithm
of the ratio of solution osmotic pressures for
calculate K (Cd = 0.5 M, Cf = 500 ppm,
Temp. of FS & DS = 30oC, pH = 7.3, Qd =
60 l/h, Qf = 60 l/h,and P= 0.5 bar).
207
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Journal of Engineering
4
4
J (l/m2.hr)
J (l/m2.hr)
3
3
2
Cf = 0.08 M
2
Qf = 20 l/h
1
1
Qf = 40 l/h
Cf = 0.16 M
0
0
1
2
0
3
0
Time (hr)
1
2
3
Time (hr)
Figure 30. Water flux with time at different
NaCl concentration in the FS (Flow rate of
FS= 20 l/h, Pressure = 9 bar, Temp. of FS =
30 oC).
Figure 31. Water flux with time at different
flow rate of FS (NaCl concentration in the
FS= 0.16 M, Pressure = 9 bar and Temp. of
FS = 30 oC).
CONCLUSIONS




Forward osmosis can be used for treating the oily wastewater from different
industries.
The water flux produced from the osmosis cell and oil concentration in FS
increase by increasing the concentration of draw solutions, the flow rate of feed
solution, and the temperature for a limit then, it decreases with increasing the
temperature and decreases by increasing the oil concentration in the feed solution
and the flow rate of the draw solutions.
The MgCl2 gives water flux higher than NaCl.
The values of resistance to solute diffusion within the membrane porous support
layer were 55.93 h/m and 26.21 h/m for NaCl and MgCl2 respectively.
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Journal of Engineering
Nomenclature
Symbols
A
B
C
CF
CP
D
dh
i
Jw
Js
K
k
p
Rg
R
T
Definition
Units
l/m2.h.bar
water permeability constant
salt permeability coefficient
concentration
conentration of feed side
conentration of permeate side
solute diffusion coefficient
hydraulic diameter
dissociation factor
water flux
reverse salt flux
resistivity coefficient
mass transfer coefficient
pressure
universal gas constant
rejection Percent
temperature
m/s
g/l
g/l
g/l
m2/s
m
l/m2.h
l/m2.h
h/m
m/s
bar
J/gmol.K
o
C
GREEK SYMBOLS
πD
π D,b
π D,i
π D,m
πF
π F,b
π F,i
Osmotic pressure of the
draw solution
Osmotic pressure of the
draw solution in the
bulk
Osmotic pressure of the
draw solution on the
inside of the active
layer within the porous
support
Osmotic pressure of the
draw solution at the
membrane surface
Osmotic pressure of the
feed solution
Osmotic pressure of the
feed solution in the
bulk
Osmotic pressure of the
feed solution on the
bar
bar
bar
bar
bar
bar
bar
209
Number 7
π F,m
π
τ
ɛ
σ
Φ
Volume
20
July
-
2014
Journal of Engineering
inside of the active
layer within the porous
support
Osmotic pressure of the bar
feed solution at the
membrane surface
Osmotic Pressure
bar
Tortuosity of the
support layer
Porosity of the support
layer
Reflection Coefficient
Osmotic Coefficient
ABBREVIATION
Symbol
CP
CTA
DS
ECP
FO
FO-RO
FS
ICP
O/W
RO
TFC
W/O
Definition
Concentration Polarization
Cellulose Triacetate
Draw Solution
External Concentration
polarization
Forward Osmosis
Forward-Reverse Osmosis
Feed Solution
Internal Concentration
polarization
Oil-in-Water
Reverse Osmosis
Thin Film Composite
Water-in-Oil
Feed Solution
REFERENCES
 Achilli, A., Cath, T.Y., and Childress, A.E., 2010, Selection of inorganic-based draw
solutions for forward osmosis applications, Journal of Membrane Science, Vol. 364:
233–241.
 Achilli, A., Cath, T.Y., Childress, A.E., 2009, Power generation with pressure
retarded osmosis: An experimental and theoretical investigation”, Journal of
Membrane Science, Vol. 343: 42-52.
 Ahmed, F. H., 2007, Performance of Manipulated Direct Osmosis in Water
Desalination Process Ph.D. thesis, Baghdad University.
210
Number 7
Volume
20
July
-
2014
Journal of Engineering
 Ahmed, F. H., 2011, Forward and Reverse Osmosis Process for Recovery and Re-use
of Water from Polluted Water by Phenol, Journal of Engineering, Vol. 17, No. 4: 912928.
 Alsvik, I. L., and Hägg, M-B., 2013, Pressure Retarded Osmosis and Forward
Osmosis Membranes: Materials and Methods, Polymers, Vol. 5: 303-327.
 Alturki, A., 2013, Removal of trace organic contaminants by integrated membrane
processes for indirect potable water reuse applications, Ph. D thesis, University of
Wollongong.
 Aydiner, C., Topcu, S., Tortop, C., Kuvvet, F., Ekinci, D., Dizge, N., and Keskinler,
B., 2012, A novel implementation of water recovery from whey: Forward–reverse
osmosis” integrated membrane system”, Desalination and Water Treatment iFirst: 1–
14.
 Bamaga, O.A. , Yokochi, A. , Zabara, B. , and Babaqi, A.S. , 2011, Hybrid FO/RO
desalination system: Preliminary assessment of osmotic energy recovery and designs
of new FO membrane module configurations, Desalination 268 (2011) 163–169.
 Bujang, M., Ibrahim, N. A., and a/l Eh Rak, A., 2012, Physicochemical Quality of
Oily Wastewater from Automotive Workshop in Kota Bharu, Kelantan Malaysia,
Australian Journal of Basic and Applied Sciences, Vol. 6, No. 9: 748-752.
 Cath, T.Y., Childress, A.E., and Elimelech, M., 2006, Forward Osmosis: Principles,
Applications, and Recent Developments”, Journal of Membrane Science, Vol. 281:
70–87.
 Cheryana, M., and Rajagopalan, N., 1998, Membrane processing of oily streams.
Wastewater treatment and waste reduction, Journal of Membrane Science, Vol. 151:
13-28.
 Choi, J., 2011, Efficient production and application of volatile fatty acids from
biomass for fuels and chemicals,Ph.D. thesis, Kaist University.
 Digman, B.R., 2010, Surface Modification of Polybenzimidizole Membranes for
Forward Osmosis, M. Sc. thesis, The University of Toledo.
 Farah, A. Y., 2013 Application of Forward Osmosis Process in Whey Treatment,
M.Sc. thesis, University of Baghdad.
 Gray, G.T., McCutcheon, J.R., and Elimelech, M., 2006, Internal concentration
polarization in forward osmosis: role of membrane orientation, Desalination, Vol.
197: 1–8.
 Hua, F.L., Tsang, Y.F., Wang, Y.J., Chan, S.Y., Chua, H., and Sin, S.N., 2007,
Performance study of ceramic microfiltration membrane for oily wastewater
treatment, Chemical Engineering Journal, Vol. 128:169–175.
211
Number 7
Volume
20
July
-
2014
Journal of Engineering
 Kim, C., Lee, S., Shon, H.K., Elimelech, M., and Hong, S., 2012, Boron transport in
forward osmosis: Measurements, mechanisms, and comparison with reverse
osmosis”, Journal of Membrane Science 419–420: 42–48. Loeb, S., Titelman, L.,
 Korngold, E., and Freiman, J., 1997, Effect of porous support fabric on osmosis through a
Loeb-Sourirajan type asymmetric membrane, Journal of Membrane Science, Vol. 129: 243–
249.
 McCutcheon, J.R. and Elimelech, M., 2006, Influence of concentrative and dilutive
internal concentration polarization on flux behavior in forward osmosis, Journal of
Membrane Science, Vol. 284: 273-247.
 Mohammed, S.A., Faisal, I., and Alwan, M.M., 2011, Oily Wastewater Treatment
Using Expanded Beds of Activated Carbon and Zeolite, Iraqi Journal of Chemical and
Petroleum Engineering, Vol.12 No.1.
 Shamel, M.M., and Chung, O.T., 2006, Drinking Water from Desalination of
Seawater: Optimization of Reverse Osmosis System Operating Parameters, Journal of
Engineering Science and Technology, Vol. 1, No. 2: 203-211.
 Thain, J.F., 1967, Principles of Osmotic Phenomena", W Heffer & Sons Ltd, London.
 Xie, M., Price, W. E. and Nghiem, L. D., 2012, Rejection of pharmaceutically active
compounds by forward osmosis: Role of solution pH and membrane orientation,
Separation and Purification Technology, Vol. 93: 107-114.
 Yan, L., Li, Y.S., Xiang, C.B., and Hong, L.J., 2006, Treatment of oily wastewater by
organic–inorganic composite tubular ultrafiltration (UF) membranes, Desalination,
Vol. 196: 76–83.
 Zhao, S., Zou, L., 2011, Effects of working temperature on separation performance,
membrane scaling and cleaning in forward osmosis desalination, Desalination, Vol.
278: 157–164.
212
‫قائمة المحتويات‬
‫القسم العربي‪:‬‬
‫العنوان‬
‫معالجة المياه المطروحة من مصافي بيجي ألعادة تدويرها لألغراض الزراعية‬
‫رافع جمال يعقوب‬
‫الصفحة‬
‫‪11 -1‬‬
‫‪2014‬‬
‫‪Journal of Engineering‬‬
‫‪July‬‬
‫‪-‬‬
‫‪20‬‬
‫‪Volume‬‬
‫‪Number 7‬‬
‫معالجة المياه المطروحة من مصافي بيجي ألعادة تدويرها لألغراض الزراعية‬
‫رافع جمال يعقوب‬
‫مدرس‬
‫قسـ العمميات النفطية‪ -‬كمية ىندسة النفط والمعادف ‪ -‬جامعة تكريت‬
‫‪E-mail: [email protected]‬‬
‫الخالصة‬
‫ييدؼ البحث الى معالجة المياه الصناعية المطروحة مف مصافي بيجي مف خالؿ أضافة مرحمة ثالثة وىي أضافة‬
‫وحدتيف االولى الترسيب باأللواح المتوازية ووحدة األمتزاز بالكاربوف المنشط العادة استعماليا مرة ثانية وخصوصا‬
‫لالغراض الزراعية حيث تبمغ كمية المياه المطروحة بحدود ‪ 2000‬ـ‪/3‬ساعة وتحتوي عمى مواد عضوية وعناصر ثقيمة‬
‫غير مسموح بيئيا طرحيا الى النير‪.‬‬
‫تـ الحصوؿ عمى نتائج جيدة في تخميص المياه مف المواد الضارة دوف الوصوؿ الى المواصفات المطموبة حيث كانت‬
‫نسبة األزالة بحدود ‪ %90‬مما تطمب اعادة التجارب بأستخداـ متعدد كموريد الحديديؾ لغرض الوصوؿ الى المواصفات‬
‫العالمية الالزمة العادة استخداـ المياه‪.‬أف الطريقة الكيمياوية بحقف مادة متعدد كموريد الحديديؾ في وحدة الترسيب‬
‫باأللواح المتوازية بينت كفاءتيا العالية في ازالة المواد السامة وخصوصا الفينوؿ حيث تـ الوصوؿ الى المواصفات‬
‫المطموبة لممياه لغرض أعادة تدويرىا لألستخداـ لالغراض الزراعية‪.‬‬
‫الكممات الرئيسية ‪-:‬معالجة مياه المصافي‪،‬األمتزاز بالكاربوف المنشط‪،‬الترسيب بالصفائح المتوازية‪،‬أعادة أستعماؿ‬
‫المياه المعالجة‪.‬‬
‫‪Baji Refinery Water Treatment to Reuse for Agricultural Purposes‬‬
‫‪Rafi Jamal Yacoup‬‬
‫‪Lecturer‬‬
‫‪University Of Tikrit-College of Petroleum&Minerals Engineering‬‬
‫‪E-mail: [email protected]‬‬
‫‪ABSTRACT‬‬
‫‪The purpose of this research is to treat Baiji refinery‬‬
‫‪waste water by adding‬‬
‫‪tertiary treatment which consist of two units:-Lamella precipitators & adsorption by‬‬
‫‪activated carbon,and reuse it for agricultural purposes.The treatment covers 2000 m3/hr of‬‬
‫‪water which contains organic and heavy metals impurities not recommended to drain to‬‬
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‫‪river according to Environmental rules. Good results were gained in this research and the‬‬
‫‪removal was 90% by adsorption & Lamella precipitation .This result is not according to‬‬
‫‪environmental rules so we treat the waste water by using poly ferric chlorides to remove all‬‬
‫‪the remaining phenol and be written the environmental limits for reuse the water for‬‬
‫‪agriculteral purposes.‬‬
‫‪by activated carbon,lamella‬‬
‫‪Keywords: refinery waste water treatment,adsorption‬‬
‫‪precepitation ,water reuse‬‬
‫المقدمة‬
‫تعتبر المواد اليايدروكاربونية مف اخطر المموثات الصناعية عمى اإلطالؽ في الوقت الحاضر وذلؾ لعدة أسباب منيا‪:‬‬
‫ضخامة كمياتيا وصعوبة تحمميا عف طريؽ البكتريا اضافة الى أف العديد منيا تعتبر مواداً مسرطنة ‪.‬تتوفر في جميع‬
‫المصافي العديد مف الوحدات لمعالجة المياه الصناعية المموثة ولكف في اغمب األحياف تكوف ىذه الوحدات غير قادرة‬
‫عمى جعؿ المياه الصناعية ضمف المواصفات المطموبة لذلؾ استمزـ األمر التفكير بإضافة وحدات أخرى يمكنيا التعامؿ‬
‫مع المواد اليايدروكاربونية‪ ،‬ومف ىذه الوحدات وحدات االمتزاز باستخداـ الكاربوف المنشط‪ .‬ومصفى بيجي يعاني مف‬
‫ارتفاع تراكيز المواد اليايدروكاربونية في المياه الخارجة مف وحدات معالجة المياه الصناعية بحيث تتخطى الحدود‬
‫المسموح بيا وفؽ المواصفات العراقية لذا استوجب دراسة إمكانية معالجة ىذه المياه الزالة المواد اليايدروكاربونية‬
‫باستخداـ الكاربوف المنشط الحبيبي(لطيف‪)8811.‬‬
‫يمكف تقسيـ طرؽ معالجة مياه الفضالت إلى ثالث طرؽ‪-:‬‬
‫‪ -1‬المعالجة األولية‪.‬‬
‫‪-3‬المعالجةالمتقدمة‪.‬‬
‫‪ -2‬المعالجة الثانوية‪.‬‬
‫حيث تستخدـ المعالجة األولية إلزالة المواد الصمبة العالقة مف مياه الفضالت سواء كانت ىذه المواد قابمة لمتحمؿ أو‬
‫غير قابمة لمتحمؿ فيمكف إزالة المواد الصمبة العالقة بعممية الترسيب مع إضافة بعض المخثرات أو تتـ إزالتيا باستخداـ‬
‫المناخؿ أو المرشحات والمعالجة الثانوية تكوف بطريقة التطويؼ‪ .‬وأخي اًر وحدات المعالجة المتقدمة حيث تقوـ ىذه‬
‫الوحدات بإزال ة المموثات التي يتعذر إزالتيا بالطرؽ السابقة ومف أىـ طرؽ المعالجة المتقدمة ىي عمميات االمتزاز‬
‫والتبادؿ األيوني والتناضح العكسي وضخ الكمور واألوزوف‪.‬‬
‫االمتزاز بواسطة الكاربوف المنشط تقنية مفيدة وفعالة لمعالجة المياه المموثة الصناعية وكمعالجة متقدمة لممواد الخارجة‬
‫مف وحدات المعالجة البايولوجية‪ .‬تستخدـ تقنيات االمتزاز بشكؿ واسع في مجاؿ إزالة كميات صغيرة مف المموثات‬
‫الموجودة في حجـ كبير مف المائع‪ .‬تتـ معالجة المواد الخارجة مف مصافي النفط والتي تحتوي عمى الفينوؿ والفورفوراؿ‬
‫وعناصر سامة واالمونيا بطرؽ مختمفة مثؿ األكسدة الكيميائية والفصؿ الفيزيائي والمعالجة البايولوجية (اسماعيل‬
‫‪ )8001‬استخدمت المنشط الحبيبي إلزالة الفينوؿ واالمبراليت مع ‪ XAD4‬إلزالة صبغة ألمثيميف الزرقاء إلزالة إضافة‬
‫نسب مختمفة مف حبيبات الزجاج كمادة غير مازة مع الكاربوف المنشط ومع االمبراليت لجعؿ عممية االمتزاز أكثر كفاءة‬
‫بزيادة المساحة السطحية لالمتزاز‪ ،‬وجدت الباحثة اف إضافة ‪ %5‬مف حبيبات الزجاج إلى الكاربوف المنشط الحبيبي‬
‫واالمبراليت بالتعاقب تقمؿ الوزف لكؿ مادة مازه بمقدار ‪ %5‬وزيادة لزمف التشغيؿ بمقدار ‪ .%80‬اف زيادة نسبة حبيبات‬
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‫‪Journal of Engineering‬‬
‫‪2014‬‬
‫‪July‬‬
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‫‪20‬‬
‫‪Volume‬‬
‫‪Number 7‬‬
‫الزجاج الكروية أكثر مف ‪ %60‬لكال المادتيف يجعؿ عممية االمتزاز غير كفوءة مقارنة مع استخداـ المادة ألمازة بمفردىا‬
‫وقد وجدت الباحثة أف عالقة التوازف مطابقة لمعادلة (لونكماير)لكؿ مف الفينوؿ وصبغة المثيميف الزرقاء‪.‬‬
‫قاـ الباحثاف (حميد و رحمن ‪ )8001‬باستخداـ الكاربوف المنشط المصنوع مف نشارة خشب جوز اليند إلزالة الفينوؿ مف‬
‫المياه وقد تـ إجراء التجارب عند درجة ح اررة ‪0 30‬ـ ودرجة حامضية (‪ )10-3‬وتراكيز فينوؿ (‪ )200-25‬ممغـ‪/‬لتر‬
‫وجد الباحثاف توافقاً بيف النتائج المختبرية والنماذج الرياضية (لونكماير) و (فريندلج)‪..‬‬
‫ووجد(رادوشكفج ودبمنن ‪ )8008‬أف أقصى سعة امتزاز مقدارىا ‪ 149.25‬ممغـ‪/‬غـ واثبتت النتائج اف الكاربوف‬
‫المنشط مادة مازه فعالة إلزالة الفينوؿ‪.‬‬
‫قاـ (ديميناس و دايامادوبولص‪ )8001‬بتصنيع وحدة ترشيح تجريبية لمعالجة المياة المموثة في اليوناف وقد تـ اجراء‬
‫ثالثة تجارب االولى عممية ترشيح فقط والثانية عممية ترشيح وتخثير بالشب اما التجربة الثالثة واالخيرة فكانت تشمؿ‬
‫اضافة الكاربوف المنشط بنوعيو (المسحوؽ والحبيبي) خالؿ عممية الترشيح‪ .‬تـ ازالة المطمب الكيمياوي لالوكسجيف‬
‫بنسبة ‪ %19‬وازالة المطمب الحيوي لالوكسجيف بنسبة ‪ %25‬وازالة الكدرة بنسبة ‪ %90‬وكذلؾ كانت ىنالؾ ازالة‬
‫لمعناصر الثقيمة ‪ ،‬وعندما تـ مزج عمميتي الترشيح والتخثير كانت النتائج مشابية لنتائج عممية الترشيح بدوف تخثير‪ .‬اما‬
‫في حالة اضافة مسحوؽ الكاربوف المنشط فاف ازالةالمطمب الحيوي أكثر مف ‪ %60‬ولكف كاف ىنالؾ زيادة بالضغط‬
‫عمى سطح غشاء الترشيح ‪ .‬ونتج في حالة أضافة الكاربوف الحبيبي فأف أزالة المتطمب الحيوي بنسبة ‪ %36‬بدوف اف‬
‫يسبب ارتفاعاً في الضغط وقد تـ ازالة فعالة جداً لمعناصر الثقيمة أيضاً عند استعماؿ الكاربوف المنشط الحبيبي‬
‫بينت(أبتسام ‪ )8088‬إمكانية إزالة ىذه المواد بالكامؿ مف مياه الفضالت باستخداـ أعمدة مف الكاربوف المنشط‪ .‬كذلؾ‬
‫بينت النتائج أف زمف االختراؽ وزمف االستنزاؼ يتناسباف عكسياً مع تركيز المموثات الداخمة وسرعة السائؿ الفراغية‬
‫وطردياً مع سمؾ الكاربوف المنشط‪ .‬كذلؾ فقد تبيف بأف سعة االمتزاز تتناسب طردياً مع تركيز المموثات الداخمة وسرعة‬
‫السائؿ الفراغية وقد وجد أيضا أف سمؾ مجاؿ االمتزاز الذي تـ إيجاده في ىذه الدراسة يتناسب طردياً مع سرعة السائؿ‬
‫الفراغية‪.‬‬
‫درس (مدائني‪ )8082‬أداء الترشيح المايكروي واألغشية األنتقائية في معالجة مياه المصافي المطروحة وضمف الحدود‬
‫البيئية لغرض أعادة أستخداميا لألغراض الزراعية وقد حصؿ عمى نسبة أسترجاع بجدود ‪ %95‬مع وجود كمية مف‬
‫المياه المموثة وبتركيز عالي بنسبة ‪%5‬‬
‫قاـ (توني مكين مع أخرين ‪)8080‬بمعالجة المياه المموثة بأستخداـ األلواح المتوازية كمرسب وبأستخداـ مادة األلمنيوـ‬
‫كمورو ىيدريت كمادة مخثرة ووجد أف نسبة أزالة المواد الصمبة بحدود ‪ %57‬ونسبة أزالة المتطمب الحيوي لألوكسجيف‬
‫‪ %30‬ومع فعالية عالية في أزالة عناصر الفسفور والنتروجيف‪.‬‬
‫قامت(زينة ورافع ‪ ) 8082‬بأستخداـ األلواح المتوازية في معالجة المياه المموثة وبكفاءة عالية بأستخداـ مواد طبيعية‬
‫كبديؿ عف أستخداـ الشب‪ .‬وتبيف كفاءتو العالية في تخميص المياه مف التموث‪.‬‬
‫أستخدـ متعدد كموريد الحديديؾ كمادة مزيمة لمفينوؿ مف قبؿ عدد مف الباحثيف(ولديرير وأخرين‪ )8082‬تبيف وصوؿ‬
‫الكفاءة في األزالة ‪ %99.7‬وفاقت ىذه الكفاءة عمى أستخداـ متعدد سمفات الحديديؾ وكموريد الحديديؾ‪.‬‬
‫‪3‬‬
‫‪Journal of Engineering‬‬
‫‪2014‬‬
‫‪July‬‬
‫‪-‬‬
‫‪20‬‬
‫‪Volume‬‬
‫‪Number 7‬‬
‫الفحوصات الكيمياوية لممياه المموثة‬
‫تـ الحصوؿ مف شركة مصافي الشماؿ في بيجي عمى كمية ماء بحدود (‪ 1‬ـ‪ )3‬مف الماء المطروح إلى النير لغرض‬
‫إجراء التجارب العممية عميو‪ .‬ولغرض معرفة طرؽ المعالجة اإلضافية لتحسيف الماء المطروح إلى النير البد مف إجراء‬
‫فحوصات مختبرية في مختبرات جامعة تكريت ‪ ,‬حيث تـ أستخداـ جياز لقياس قيمة الرقـ الييدروجيني ويسمى موديؿ‬
‫‪ 410‬مف صنع شركة ( ثيرمو أورينت)‬
‫وجياز األشعة فوؽ البنفسجية المستخدـ لقياس التراكيز عند األطواؿ الموجية المعينة ومف خالؿ إجراء المعايرة نتمكف‬
‫بواسطتو قياس تركيز المواد اليايدروكاربونية في المياه وىو مف ‪ UV Spectrophotometer)()V-(Model530‬وىو‬
‫ياباني المنشأ‪ .‬وتـ عمؿ معايرة لألمتصاصية مع تركيز الفينوؿ‪ .‬ونتائج فحوصات موضحة في الجدوؿ رقـ (‪)1‬‬
‫األجهزة ألمختبرية وطريقة العمل‬
‫تـ بناء منظومة البحث وحسب ما ىو موضح في الشكؿ رقـ (‪ )1‬المنظومة البحثية لعممية االمتزاز والتي تـ اعتماد‬
‫االعتبارات التصميمية في بناء المنظومة وأجريت تجارب عديدة لتقميؿ نسبة الفينوؿ في المياه‪.‬‬
‫مع األخذ بنظر االعتبار عند بناء الجياز ألمختبري إمكانية التحكـ بأىـ العوامؿ التي تؤثر عمى عممية االمتزاز وىي‬
‫كؿ مف سرعة السائؿ الفراغية المرتبطة بمعدؿ الجرياف ومساحة المقطع العمودي عمى الجرياف وسمؾ طبقة الكاربوف‬
‫وتركيز المموثات الداخمة لمجياز‪ .‬أما درجة الح اررة فقد أنجزت جميع التجارب ضمف درجة ح اررة المختبر لكوف ذلؾ ىو‬
‫واقع الحاؿ في المؤسسات الصناعية حيث يشكؿ رفع أو خفض درجات الح اررة لممياه المموثة قبؿ معالجتيا كمفة‬
‫اقتصادية عالية ال يمكف تحمميا‪.‬‬
‫تـ تصنيع عمود االمتزاز بطوؿ ‪50‬سـ وقطره يساوي ‪2‬سـ وىو دائري الشكؿ مصنوع مف مادة البايركس ‪ ،‬و لمتحكـ‬
‫بسمؾ طبقة الكاربوف التي تستقر فوؽ قطعةخزفية مثقبة يتـ اعادة تدوير الماء لمحصوؿ عمى ارتفاع اضافي (‪ 60‬سـ و‬
‫‪ 90‬سـ )‪ .‬وقد تـ اختيار معدؿ الجرياف باالعتماد عمى األعتبارات التصميمية وتتراوح ما بيف ‪ 6-2‬لتر‪/‬ساعة‪ .‬أما‬
‫بالنسبة لطوؿ العمود أف كؿ أعمدة االمتزاز يتـ ترؾ مسافة لألسفؿ وتترؾ مسافة لألعمى وىذا لمغسؿ العكسي يحتاج‬
‫إلى فراغ فوؽ الطبقة المحشوة يصؿ إلى ‪10‬سـ لذلؾ تركنا ىذا الفراغ في العمود‪.‬‬
‫يوضح الشكؿ رقـ (‪ )2‬مخططاً لجياز الترسيب باأللواح المتوازية والشكؿ يمثؿ صورة لمجياز الذي يتألؼ مف عدة‬
‫أجزاء يمث ؿ الجزء األوؿ منيا حجرة التخثير والجزء الثاني يمثؿ حجرة التمبيد ‪ ،‬أما الجزء الثالث فيمثؿ حجرة الترسيب‬
‫التي تحتوي عمى صفائح مائمة بزاوية ‪ .60‬تفصؿ بيف صفيحة وأخرى مسافة متغيرة حيث تكوف بالقسـ األوؿ ‪ 4‬سـ أما‬
‫في القسـ الثاني فتكوف المسافة بيف الصفائح ‪ 2‬سـ‪.‬‬
‫يح توي الجياز إضافة لذلؾ عمى خزاف الماء المراد معالجتو وخزاف الماء المعالج ‪ ،‬إضافة إلى مضخة وعدد مف‬
‫يبيف مواصفات جياز الترسيب ذي الصفائح المائمة المستخدـ‬
‫الصمامات لمسيطرة عمى جرياف الماء‪ .‬الجدوؿ (‪ّ )3‬‬
‫طريقة العمل في جهاز الترسيب ذو الصفائح المائمة‬
‫تـ تييئة الماء المموث أو الماء الخارج مف وحدة األمتزاز بالكاربوف المنشط ‪.‬‬
‫‪4‬‬
‫‪2014‬‬
‫‪Journal of Engineering‬‬
‫‪July‬‬
‫‪-‬‬
‫‪20‬‬
‫‪Volume‬‬
‫‪Number 7‬‬
‫ تـ إضافة كميات محددة مف المواد الكيمياوية المستعممة في البحث (مثؿ مادة الشب او متعدد كموريد الحديديؾ) إلى‬‫حجرة المزج السريع ‪ ،‬ينتقؿ الماء بعدىا إلى حجرة التمبيد ‪.‬‬
‫‪ -‬بعدىا يدخؿ الماء إلى حجرة الترسيب وبمعدؿ جرياف يتـ السيطرة عميو بواسطة المضخة‪.‬‬
‫النتائج والمناقشة‬
‫إف أىـ العوامؿ التي تؤثر عمى عممية االمتزاز ىي معدؿ الجرياف وسمؾ طبقة المادة ألمازة وطبيعة وتركيز المادة‬
‫الممتزة (تـ أستخداـ الماء المموث المطروح مف مصافي النفط في بيجي الى النير وبتركيز ثابت مفحوص وىو ‪( 8‬ممغـ‬
‫‪/‬لتر) ولمادة الفينوؿ‪.‬‬
‫إف زمف التماس عامؿ ميـ في تصميـ عمود االمتزاز ذي الطبقة الثابتة ولذلؾ فأف سمؾ الطبقة وسرعة السائؿ الفراغية‬
‫ىما العامالف الرئيسياف في التصميـ‪.‬‬
‫نالحظ مف الشكؿ رقـ (‪ )3‬انو عند زيادة معدؿ الجرياف بثبوت سمؾ الطبقة فأف تركيز الفينوؿ الخارج يزداد وذلؾ‬
‫لعدة أسباب منيا عدـ وجود الوقت الكافي لحدوث االمتزاز و وجود مساحات معينة وحجـ معيف مف الكاربوف غير‬
‫مغطاة ولذلؾ ال يحدث االمتزاز عميو وبذلؾ تتكوف مناطؽ نقية مف الكاربوف المنشط أي مواقع أمتزاز فارغة‪ .‬ولكف‬
‫عندما يكوف معدؿ الجرياف قميمة أي وقت التماس كبي اًر فأف ذلؾ سيؤدي إلى إتاحة الوقت الكافي المتزاز كمية اكبر مف‬
‫المموثات وىذا يؤدي إلى شبو تشبع الكاربوف المنشط بالمواد المموثة قبؿ االنتقاؿ إلى الجزء األخر مف الطبقة مما يعني‬
‫إف كمية المادة الممتزة تكوف اكبر في ىذه الحالة‪.‬‬
‫إف سمؾ طبقة الكاربوف أىمية كبيرة في عممية االمتزاز ‪ ,‬ويتضح مف الشكؿ رقـ(‪ )4‬أف قمة سمؾ الطبقة تؤدي إلى‬
‫زيادة تركيز الفينوؿ الخارج‪ .‬أما زيادة سمؾ طبقة الكاربوف فأنيا تعني زيادة كمية الكاربوف أي زيادة المواقع المتاحة‬
‫لالمتزاز وىذا ما يقمؿ مف تركيز تركيز الفينوؿ الخارج كذلؾ زيادة السمؾ تؤدي إلى تقميؿ ظاىرة ترؾ مساحات فارغة‬
‫لكونو يتيح وقت أكثر لمماء المموث لمتماس مع الكاربوف‪.‬‬
‫اف زيادة سمؾ طبقة الكاربوف تؤدي إلى امتزاز كمية مواد ىايدروكاربونية أكثر وبالتالي يتـ استيالؾ الكاربوف بصورة‬
‫كاممة والذي يؤدي إلى استنزاؼ الكاربوف وبذلؾ يفقد عمود االمتزاز فائدتو بحيث يخرج الماء المموث بدوف معالجة‬
‫وتتساوى‬
‫المموثات‬
‫تراكيز‬
‫الداخمة‬
‫وعندىا‬
‫والخارجة‬
‫يحتاج‬
‫الشكؿ رقـ (‪ )5‬وىي تمثؿ منحنيات االمتزاز لمفينوؿ عند سمؾ كاربوف منشط مقداره ‪35‬سـ‪ .‬نالحظ مف ىذه األشكاؿ‬
‫انو عند زيادة سرعة السائؿ الفراغية بثبوت سمؾ الطبقة فأف نقطة االختراؽ ستظير مبكرة أي يحدث االختراؽ بسرعة‬
‫وذلؾ لعدة أسباب منيا عدـ وجود الوقت الكافي لحدوث االمتزاز و وجود مساحات معينة وحجـ معيف مف الكاربوف غير‬
‫مغطاة ولذلؾ ال يحدث االمتزاز عميو وبذلؾ تتكوف مناطؽ نقية مف الكاربوف المنشط أي مواقع أمتزاز فارغة‪ .‬ولكف‬
‫عندما تكوف قميمة أي وقت التماس كبي اًر فأف ذلؾ سيؤدي إلى إتاحة الوقت الكافي المتزاز كمية اكبر مف المموثات وىذا‬
‫يؤدي إلى شبو تشبع الكاربوف المنشط بالمواد المموثة قبؿ االنتقاؿ إلى الجزء األخر مف الطبقة مما يعني إف كمية المادة‬
‫الممتزة تكوف اكبر في ىذه الحالة‪ .‬ومف المالحظ أيضاً أف زيادة سرعة السائؿ الفراغية تقمؿ حجـ الماء المعالج إلى أف‬
‫يتـ حدوث االختراؽ‬
‫إلػ ػػيو(أبتسام‪.)8088‬أف‬
‫وتقمؿ زمف التماس بيف المادة المذابة والمػ ػػادة ألمازة وىذا مػػتوافؽ مػ ػ ػػع ما توصمت‬
‫تشبع‬
‫الكاربوف‬
‫المنشط‬
‫‪5‬‬
‫بالمموثات‬
‫يتـ‬
‫أعادة‬
‫تنشيطو‬
‫بالتسخيف‬
‫‪Journal of Engineering‬‬
‫‪2014‬‬
‫‪July‬‬
‫‪-‬‬
‫‪20‬‬
‫‪Volume‬‬
‫‪Number 7‬‬
‫أما حوض الترسيب باأللواح المتوازية فأف تشبعو بالمموثات فيتـ التخمص منيا مف خالؿ تفريغ الحوض ودفع المياه‬
‫المموثة والمشبعة بالمموثات الى أحواض تجفيؼ بالطاقة الشمسية وىي عممية أقتصادية وفعالة لمتخمص مف المياه‬
‫المموثة‪.‬‬
‫تـ ربط منظومة الترسيب باأللواح المتوازية مع الخارج مف وحدة األمتزاز بالكاربوف المنشط وتـ أضافة متعدد كموريد‬
‫الحديديؾ وبتركيز قميؿ(‪ 25-10‬ممغـ ‪/‬لتر) لغرض أزالة الكمية المتبقية مف الفينوؿ وتـ الحصوؿ عمى مياه معالجة‬
‫تنطبؽ عمييا شروط المياه المستخدمة لألغراض الزراعية وحسب الجدوؿ رقـ(‪ )2‬النوع (ب) مع األحذ بنظر األعتبار‬
‫أف تركيز الفينوؿ يقترب مف الصفر‪..‬وجميع ىذه التجارب أجريت في منظومة األلواح المتوازية مف خالؿ حقف كمية‬
‫محددة مف متعدد كموربد الحديديؾ وتـ األكتفاء بقياس نسبة الفينوؿ في المياه الخارجة مف منظومة األلواح المتوازية‬
‫وكانت قريبة الى الصفر وىي تتطابؽ مع نتائج الباحثيف(ولديرير وأخرين‪.)8082‬‬
‫االستنتاجات‬
‫‪ -1‬إف تركيز المموثات المدروسة لمياه مصفى بيجي الخارجة مف جميع وحدات المعالجة ال تزاؿ مرتفعة جداً وىي‬
‫خارج الحدود المسموح بيا وفؽ المواصفات العراقية‪.‬‬
‫‪ -2‬إمكانية تقميؿ تراكيز قسـ محدد مف المموثات إلى الحدود المسموح بيا وفؽ المواصفات العراقية باستخداـ الكاربوف‬
‫المنشط الحبيبي ولكف ضمف ىذه المواصفات ال يمكف استخداـ ىذه المياه لإلغراض الزراعية وحسب الجدوؿ رقـ(‪.)2‬‬
‫‪ -3‬أف أفضؿ معدؿ جرياف ىو ‪ 2‬لتر‪/‬ساعة‪.‬‬
‫‪ -4‬اف معدؿ الجرياف التي ليا عالقة بزمف التماس وسمؾ الكاربوف المنشط ليا تأثي اًر ميما عمى عممية االمتزاز‪.‬‬
‫‪ -5‬يتناسب تركيز الفينوؿ الخارج عكسيا مع سمؾ طبقة الكاربوف المنشط وطردياً مع معدؿ الجرياف‪.‬‬
‫‪ -6‬أف أستخداـ مادة متعدد كموريد الحديديؾ يساعد عمى أزالة الكمية المتبقية مف الفينوؿ‬
‫المصادر‬
‫لطيؼ حميد عمي‪" ،‬التموث الصناعي"‪ ،‬دار الكتب لمطباعة والنشر جامعة الموصؿ‪ ،‬صفحة (‪.1987 ، )188 -184‬‬
‫‪Dialynas, E. and Diamadopoulos, E, "Integration of Immersed Membrane Ultra-filtration‬‬
‫‪with Coagulation and Activated Carbon Adsorption for Advanced Treatment of Municipal‬‬
‫‪Waste Water", Department of Environmental Engineering, Technical university of crete,‬‬
‫‪chania, Greece, 2008.‬‬
‫‪6‬‬
Number 7
Volume
20
July
-
2014
Journal of Engineering
Hameed, B. H., and Rahman, A., "Removal of phenol from aqueous Solution by
Adsorption onto Activated Carbon Prepared from Biomass Material", Applied science
publishers LTD, Essex, chapter 3, PP. (49-84), 2008.
Ibtisam A. Jaddo," Study of Using Granular Activated Carbon For Removing Phenol,
Parachlorophenol, and Benzene From Wastewater of Baiji Refinery", Department of
chemical engineering, University of Tikrit, 2011.
Ismail, Sh., "Evaluation of Heterogeneous Adsorbents Bed for the Removal of Organic
Materials from Water", Ph. D. Thesis, university of Baghdad P. (4-39), Iraq, 2008.
Madaeni
S.S,"Membarance Treatment of Oily Waste Water From Refinery
Processes",Asia Pacific Journal of Chemical Engineering,8,(45-53), 2013.
Wilderer,A."Evolution of Sanitation & waste treatmenttechnologies through the centeries",
2014, ISBN9781780404844.
WWW.ress.com,vol.113,IssB,1,25
‫نتائج الفحوصات المختبرية لممياه المطروحة إلى النهر من مصافي بيجي‬. 1‫جدول رقم‬
‫الفحص‬
‫القيمة‬
‫الفحص‬
‫القيمة‬
pH
8.65
Cd, mg/l
<0.1
Cond., ms
2.39
Cr, mg/l
<0.1
122
Cu, mg/l
0.19
640
Fe, mg/l
0.6
80
Pb, mg/l
<0.1
zero
Ni, mg/l
0.15
120
Ag, mg/l
<0.05
8
Oil
7.5
Cl- ,mg/l
Hardness ,mg/l
SO4- ,mg/l
OH- ,mg/l
(HCO3-,CO3-),mg/l
Phenol, mg/l
7
Number 7
Volume
20
July
-
2014
‫ مخطط لجهاز األمتزاز‬. 1 ‫شكل رقم‬
8
Journal of Engineering
‫‪2014‬‬
‫‪Journal of Engineering‬‬
‫‪July‬‬
‫‪-‬‬
‫‪20‬‬
‫‪Number 7‬‬
‫‪Volume‬‬
‫جدول رقم ‪ . 2‬الحدود القصوى المسموح بها لممعايير القياسية الخاصة بالمياه المعالجة المستخدمة ألغراض الري‬
‫األشجار‬
‫المحاصيؿ‬
‫الحرجية‬
‫الصناعية‬
‫الحبوب‬
‫والمحاصيؿ‬
‫العمفية‬
‫جوانب‬
‫المسطحات‬
‫الطرؽ‬
‫الخضراء‬
‫الخارجية‬
‫األشجار المالعب‬
‫المثمرة‬
‫الرياضية‬
‫المتنزىات‬
‫الخضار‬
‫والمالعب المطبوخة‬
‫المؤشر‬
‫ج‬
‫ب‬
‫أ‬
‫المؤشر‬
‫‪150‬‬
‫‪100‬‬
‫‪30‬‬
‫)‪BOD5(mg/l‬‬
‫‪300‬‬
‫‪200‬‬
‫‪75‬‬
‫)‪COD(mg/l‬‬
‫‪-‬‬
‫‪-‬‬
‫أكبر مف ‪4‬‬
‫)‪DO(mg/l‬‬
‫‪-‬‬
‫‪1500‬‬
‫‪15000‬‬
‫)‪TDS(mg/l‬‬
‫‪150‬‬
‫‪150‬‬
‫‪50‬‬
‫)‪SS(mg/l‬‬
‫‪-‬‬
‫‪-‬‬
‫‪0.5‬‬
‫‪25‬‬
‫‪25‬‬
‫‪20‬‬
‫‪-‬‬
‫‪5‬‬
‫‪3‬‬
‫‪9‬‬
‫‪SAR‬‬
‫‪9-6‬‬
‫‪pH‬‬
‫جدول رقم ‪ . 3‬مواصفات جهاز الترسيب ذو الصفائح‬
‫زاوية ميؿ الصفائح‬
‫معدؿ الجرياف‬
‫‪60‬‬
‫(‪-55‬‬
‫ارتفاع الجياز‬
‫مساحة‬
‫‪24‬‬
‫)لتر‬
‫\ساعة‬
‫‪ 100‬سـ‬
‫‪2‬‬
‫‪ 12837‬سـ‬
‫الترسيب‬
‫لحجرة الترسيب‬
‫عرض الجياز‬
‫‪ 120‬سـ‬
‫سمؾ الجياز‬
‫‪ 25‬سـ‬
‫‪9‬‬
‫‪CL2residual‬‬
‫‪NO3-N‬‬
‫)‪(mg/l‬‬
‫‪NH4-N‬‬
‫)‪(mg/l‬‬
‫‪2014‬‬
‫‪Journal of Engineering‬‬
‫‪-‬‬
‫‪July‬‬
‫‪Volume‬‬
‫‪20‬‬
‫‪Number 7‬‬
‫شكل رقم‪ .8‬جهاز الترسيب ذو الصفائح‬
‫جدول ‪ .2‬بعض الخواص الفيزياوية لمكاربون المنشط الحبيبي‬
‫القيمة‬
‫الخاصية‬
‫‪3‬‬
‫الكثافة‬
‫‪ 482.025‬كغـ‪/‬ـ‬
‫المسامية‬
‫‪0.41‬‬
‫قطر الحبيبية‬
‫(‪ )3-2‬ممـ‬
‫المساحة السطحية‬
‫‪1175.62‬ـ ‪/‬غـ‬
‫‪10‬‬
‫‪2‬‬
‫‪Journal of Engineering‬‬
‫‪2014‬‬
‫‪-‬‬
‫‪July‬‬
‫‪20‬‬
‫‪Volume‬‬
‫‪Number 7‬‬
‫شكل رقم ‪ .2‬تأثير معدل التدفق عمى تركيز الفينول المزال من الماء المموث‬
‫شكل رقم‪ .2‬تأثير سمك طبقة الكاربون عمى تركيز الفينول المزال من الماء‬
‫‪11‬‬
Number 7
Volume
20
July
-
2014
Journal of Engineering
1.2
LHSV=0.5
1
LHSV=1.5
LHSV=3
c/co
0.8
LHSV=25
LHSV=75
0.6
LHSV=129
0.4
0.2
0
0
10
20
30
40
50
time.hr
)‫سم‬25= ‫ منحنيات االمتزاز لمفينول عمى الكاربون المنشط (السمك‬.5 ‫شكل رقم‬
12
60
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