Geocentrix 1.7 ReActiv User Manual
Below you will find brief information for ReActiv 1.7. The program describes the design method given in the UK Highways Agency’s Advice Note HA68 on Design methods for the reinforcement of highway slopes by reinforced soil and soil nailing techniques. To stabilize the slope as well as the Tmax and Tob mechanisms, you can calculate the depth, length, and spacing of the reinforcement needed. For preliminary design, the suggested layout is suitable and the procedure is discussed further. The program has the capability to analyze reinforced slopes in a variety of different soil types, using reinforced soil or soil nails.
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ReActiv
Version 1.7
User Manual
REINFORCED SLOPE DESIGN
2 ReActiv 1.7 User Manual
Information in this document is subject to change without notice and does not represent a commitment on the part of Geocentrix Ltd. The software described in this document is furnished under a licence agreement or non-disclosure agreement and may be used or copied only in accordance with the terms of that agreement. It is against the law to copy the software except as specifically allowed in the licence or non-disclosure agreement. No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, for any purpose, without the express written permission of Geocentrix Ltd.
Screenshots may differ from those shown in this document.
©1994-2012 Geocentrix Ltd. All rights reserved.
Geocentrix, ReActiv, and ReWaRD are registered trademarks of Geocentrix Ltd.
Microsoft and Windows are registered trademarks of Microsoft Corporation. IBM is a registered trademark of International Business Machines Corp. Other brand or product names are trademarks or registered trademarks of their respective holders
Set in Optimum using Corel WordPerfect X5.
Update 0 (06/12).
Printed in the UK.
Acknowledgements
Acknowledgments
ReActiv was designed and written by Dr Andrew Bond of Geocentrix, based on theory developed by Drs Jerry Love and George Milligan of the Geotechnical
Consulting Group (GCG).
Version 1.0 of the program was tested by Rob Nyren (formerly at GCG) and Dr Ken
Brady and Doug Boden of the Transport Research Laboratory. Version 1.5 was tested by Cedric Allenou (formerly at GCG).
The documentation was written by Andrew Bond, Jerry Love (of GCG), and Romain
Arnould (formerly at GCG).
Professor David Hight of GCG helped design the database of critical state soil parameters.
3
4 ReActiv 1.7 User Manual
Table of contents
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Table of contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Chapter 1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
About this book
Conventions
Where to go for help
9
10
11
ReActiv’s help system
Tooltips
Technical support
Sales and marketing information
11
11
11
11
Chapter 2
Installing and running ReActiv . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
What’s in the ReActiv package
Hardware and software requirements
Upgrading from an earlier version of ReActiv
To install ReActiv
To run ReActiv
12
12
12
12
12
Chapter 3
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Job View
Slope
13
13
Soil column
Water regime
Surcharge
14
14
14
Datum line
Rulers
Managers
Mechanisms View
Reinforcement View
Toolbar
Status Bar
Soils
15
16
16
16
14
14
15
15
Soil Manager
Soil classification system and database
The selected soil
Design parameters
Slopes
Stability of upper slopes/crests
Water regimes
Parallel water regime
Horizontal water regime
Parabolic water regime
Reinforcements
Reinforcement Manager
Design strength
Design factors
Calculation options
Interwedge friction factor
Project information
19
19
19
20
20
21
21
21
22
18
18
19
19
17
17
18
18
Table of contents 5
Printing
Print preview
Customizing the program
Chapter 4
Tutorial 1: embankment in dense sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Embankment in dense sand
Creating a project
Running the program
24
24
24
Defining the soil
Creating a new soil
Soil properties
Classifying the soil
24
24
25
25
Entering soil properties
Defining the slope
Viewing the slope
Defining the reinforcement
Calculating the reinforcement
Reviewing the results
Reviewing the reinforcement layout
Reviewing the mechanisms
Clearing the results
Printing the results
Controlling the printer
25
26
26
26
27
27
27
28
28
29
29
29
22
22
22
23
Chapter 5
Tutorial 2: cutting in stiff clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Cutting in stiff clay
Creating the document
30
30
Running the program
Creating a new project
Defining soil properties
Using the Soil Manager
30
30
30
30
Creating the new soil
Classifying the soil
Entering soil properties
Defining the slope
Viewing the slope
Defining the water regime
Defining the reinforcement
Using the Reinforcement Manager
Creating the new reinforcement
Calculating the reinforcement
Searching for the T max
Searching for the T ob
mechanism
mechanism
Calculating the required reinforcement
Reducing the nail lengths
Visualizing the layout
32
32
32
32
31
31
31
32
33
33
33
34
35
35
35
Chapter 6
Tutorial 3: fixed vertical spacings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Fixed vertical spacings
Creating the project
Running the program
Creating a new project
37
37
37
37
6 ReActiv 1.7 User Manual
Defining soil properties
Defining the slope
Defining the water regime
Defining the surcharge
Defining the reinforcement
Using the Reinforcement Manager
Creating the new reinforcement
Calculating the reinforcement layers
Setting the calculation options
Performing the calculation
Chapter 7
Calculating mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Mechanisms View 41
Mechanism types
Distribution of reinforcement force
Baseline
41
42
43
Invalid mechanisms
Calculating single mechanisms
Calculating grid mechanisms
Minimum and maximum co-ordinates
Number of lines
Spacing
Automatic grid
Default grid
Critical mechanisms
Search algorithm
Calculating the T max
Searching for T
mechanism max
Search algorithms
Calculating the T ob
Searching for T
mechanism ob
Search algorithm
45
45
45
46
43
43
44
45
47
47
47
48
46
46
47
47
37
38
38
38
38
38
39
39
39
40
Chapter 8
Calculating the required reinforcement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Reinforcement View
Calculating the required reinforcement
Minimizing the length of soil nails
49
49
50
Providing an additional layer at the top of the slope
Setting a the vertical spacing between the layers
Tension on Wedge 1 or 2
50
50
51
Chapter 9
Background theory and assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Two-part wedge mechanism with horizontal reinforcement
Factors-of-safety
Governing equations
Equations with zero interwedge friction
52
53
53
53
Equations with interwedge friction
.
1
or .
2
?
Interwedge friction angle
Critical mechanism
T
T max
mechanism ob
mechanism
Required reinforcement
Number of layers
55
55
55
56
54
54
55
55
Table of contents 7
Depth to the first layer
Pullout length of the first layer
Normal effective stress
Depths of layers 2-n
Further checks
Two-part wedge mechanism with inclined reinforcement
Governing equations
.
1
or .
2
T max*
T o*
?
mechanism
mechanism
Required reinforcement
Normal effective stress
Base-sliding resistance
Compatibility with the Advice Note
Pullout resistance
Compatibility with the Advice Note
Minimizing soil nail pullout lengths
Special considerations for Two-part slopes
Surcharges
Compatibility with the Advice Note
Chapter 10
Proceeding to a final design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Checking individual mechanisms
Competent foundation
66
66
Front facing
Checking pullout of the base layer
Elongation of reinforcement
Drainage
Inherent conservatism of a frictionless interwedge boundary
Using ReActiv to check other design methods
67
68
66
66
66
67
Chapter 11
Comparison with published results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Horizontal reinforcement 69
Inclined reinforcement 71
Chapter 12
Further examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Supplied examples
Example 1: embankment in dense sand
73
73
Example 2: embankment in stiff clay
T ob
mechanism
Required reinforcement
Example 3: cutting in stiff clay
Example 5: slip repair in stiff clay
T max
T ob
mechanism
mechanism
Required reinforcement
73
74
74
74
74
75
75
75
Example 6: cutting with unstable upper slope
Analysing two-part slopes
T max
T ob
mechanism
mechanism
Required reinforcement
Example 7: upper slope of Example 6
T max
T ob
mechanism
mechanism
76
76
77
77
75
75
76
76
59
60
61
61
58
59
59
59
57
57
57
57
58
58
58
62
62
63
64
65
8 ReActiv 1.7 User Manual
Required reinforcement 77
Chapter 13
Soil Classification System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Database of soil properties 79
Chapter 1: Introduction
Chapter 1
Introduction
Welcome to ReActiv®, the reinforced slope design program. ReActiv is an interactive program that helps you to design reinforced slopes in a variety of different soil types, using reinforced soil or soil nails.
This chapter of the ReActiv User Manual outlines the contents of this book, explains the conventions that are used herein, and tells you what to do if you need help using the program.
About this book
This User Manual is divided into the following chapters:
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Introduction
Installing and running ReActiv
Overview
Tutorial: worked example 1
Tutorial: worked example 2
Tutorial: worked example 3
Calculating mechanisms
Calculating the required reinforcement
Chapter 9
Background theory and assumptions
Chapter 10
Proceeding to a final design
Chapter 11
Comparisons with published results
Chapter 12
Further examples
Chapter 13
Soil Classification System
9
10 ReActiv 1.7 User Manual
Conventions
To help you locate and interpret information easily, the ReActiv User Manual uses the following typographical conventions.
This
Bold
Item1 > Item2
italic
monospaced
CAPITALS
KEY1+KEY2
KEY1, KEY2
Represents
Items on a menu or in a list-box; the text on a button or next to an edit control; or the label of a group box.
An item on a cascading menu. Item1 is the name of an option on the main menu bar (such as File or Window); and Item2 is the name of an option on the cascading menu that appears when you select Item1 (such as New or Open). Thus, File > New represents the New command from the File menu.
Placeholders for information you must provide. For example, if you are asked to type filename, you should type the actual name for a file instead of the word shown in italics.
Italic type also signals a new term. An explanation immediately follows the italicized term.
Anything you must type on the keyboard.
Directory names, filenames, and acronyms.
An instruction to press and hold down key 1 before pressing key 2.
For example, "ALT+ESC" means press and hold down the ALT key before pressing the ESC key. Then release both keys.
An instruction to press and release key 1 before pressing key 2. For example, "ALT, F" means press and release the ALT key before pressing and releasing the F key.
Chapter 1: Introduction 11
Where to go for help
Your first source of help and information should be this manual and the ReActiv’s extensive help system.
ReActiv’s help system
ReActiv’s help system contains detailed information about all aspects of the program.
Help appears in a separate window with its own controls. Help topics that explain how to accomplish a task appear in windows that you can leave displayed while you follow the procedure.
To open the help system:
Press F1
Click the Help button in any dialog box
Choose a command from the Help menu
If you need assistance with using the help system, choose the How To Use Help command from the Help menu.
Tooltips
If you pause while passing the mouse pointer over an object, such as a toolbar button, ReActiv displays the name of that object. This feature, called tooltips, makes it easier for you to identify what you see and to find what you need.
Technical support
Technical support for ReActiv is available direct from Geocentrix or through your local distributor. If you require technical support, please contact Geocentrix by any of these means:
Voice: +44 (0)1737 373963
Fax: +44 (0)1737 373980
Email: [email protected]
Web: www.geocentrix.co.uk
Please be at your computer and have your licence number ready when you call.
Alternatively, you can write to the following address:
ReActiv Technical Support
Geocentrix Ltd
Scenic House
54 Wilmot Way
Banstead
Surrey
SM7 2PY
United Kingdom
Please quote your licence number on all correspondence.
Sales and marketing information
For sales and marketing information about ReActiv, please contact ReActiv Sales on the same numbers as above.
12 ReActiv 1.7 User Manual
Chapter 2
Installing and running ReActiv
ReActiv can be installed to run on most Windows operating systems, but has been tested on Windows XP and Windows 7. Although you can install the software on as many computers as you like, you will only be able to run the program on those computers to which you attach the supplied security key.
Before you begin installing your copy of ReActiv, there are a few things you should check:
Examine the contents of your ReActiv package to check we have sent you everything listed below
Make sure you have the necessary hardware and software to run ReActiv
What’s in the ReActiv package
The ReActiv package includes the following items:
ReActiv User Manual (this document)
Geocentrix Software CD
One security key (dongle) for each copy of the program you have purchased
Instructions for installing and running your copy of ReActiv
Hardware and software requirements
In order to run ReActiv, you will need the following hardware and software:
IBM®-compatible PC with an 80386- (or higher) processor
Microsoft® Windows® XP (or later)
At least 9Mb free space on your hard disk for a typical installation
CD-ROM drive
Any printer supported by Windows
A mouse or other pointing device supported by Windows
Upgrading from an earlier version of ReActiv
If you are upgrading your copy of ReActiv from an earlier version, you should note the following:
ReActiv’s setup program installs Version 1.7 in a different directory to Versions
1.0, 1.5, and 1.6 and hence will not overwrite your existing copy of ReActiv
RAV files created in ReActiv 1.0 cannot be read by ReActiv 1.7, owing to an internal restructuring of ReActiv’s data files
RAV files created in ReActiv 1.5 and 1.6 can be read by ReActiv 1.7
To install ReActiv
Instructions for installing ReActiv on Windows systems are provided separately to this User Manual. Please refer to those instructions for further details or contact
Geocentrix for assistance.
To run ReActiv
From Windows’ Start menu, click All Programs > Geocentrix > ReActiv 1.7.
Chapter 3: Overview 13
Chapter 3
Overview
This chapter of the ReActiv User Manual provides an overview of ReActiv. It describes the main features of the program and the most commonly used commands.
ReActiv implements and extends the design method given in the UK Highways
Agency’s Advice Note HA68 on Design methods for the reinforcement of highway
slopes by reinforced soil and soil nailing techniques (1994), which can be found in the
HA’s Design manual for roads and bridges, Volume 4 Geotechnics and drainage,
Section 1 Earthworks, Part 4. For brevity, this document is referred to herein as the
Advice Note. Chapter 9 explains the background theory and assumptions behind the
Advice Note.
ReActiv divides the display of information about your reinforced slope problem between three main views:
The Job View — allows you to define the problem that you want to analyse
The Mechanisms View — displays the results of calculations using the two-part wedge mechanism
The Reinforcement View — gives a preliminary layout of the reinforcement that will be required
Each of these views is displayed in its own window, which fits inside ReActiv’s Frame
Window. The Frame Window serves as a desktop on which all other views and windows are arranged.
The following sections describe the various views and windows in turn.
Job View
The Job View is place where you enter information that defines your reinforced slope problem. ReActiv provides you with continuous feedback as you enter this information, by displaying an up-to-date picture of the slope being analysed, including the soil column, water table, and any surcharge applied to the slope.
Slope
The slope is shown at the centre of the Job View and is drawn to a true scale. The names given to various parts of the slope are indicated below.
14 ReActiv 1.7 User Manual
Soil column
The Selected Soil (see page 18) is shown by the soil column near the left hand edge of the Job View. The symbol used to represent the Selected Soil depends on its classification.
The soil column is drawn to a true vertical scale.
Water regime
The slope’s water regime is represented by Bishop’s pore pressure parameter (r u
The current value of r u
is displayed underneath the slope’s baseline.
).
Surcharge
Surcharges are shown by (red) down-pointing arrows. They can be applied to the horizontal crest of One- or Two-part slopes or to the sloping crest of Infinite slopes.
They cannot be applied to the lower part of any slope or the upper part of a Two-
part slope.
The magnitude of the surcharge appears above the surcharge symbol.
Datum line
If the appropriate option on the View menu is selected, a datum line is drawn vertically through the toe of the slope. The datum line is coloured grey.
Rulers
Heights above ground level can be measured using the vertical ruler that appears along the left hand edge of the Job View (if the appropriate option on the View menu is selected). Similarly, horizontal distances can be measured using the horizontal ruler that appears along the top edge of the Job View.
You can change the scale of the rulers (and hence the size of the drawing in the Job
View) by:
Positioning the mouse pointer over one of the rulers and then clicking the right mouse button. A pop-up menu appears. Choose the scale you want from those listed
Choosing one of the scales on the View menu
Choosing Zoom In or Zoom Out on the View menu to change the scale to its next level up or down
Clicking on the Zoom In or Zoom Out buttons on the Toolbar
The scales that ReActiv provides are:
1:50
1:100
1:250
Chapter 3: Overview
1:500
15
Managers
ReActiv’s Managers are floating dialog boxes that allow you to add, edit, and delete objects with a minimum of effort. Each Manager displays a list of all the objects of a particular type you have defined. See page 17 for further information about
ReActiv’s Soil Manager and page 20 for ReActiv’s Reinforcement Manager.
Mechanisms View
The Mechanisms View displays the results of your calculations using the two-part wedge mechanism described in Chapter 2.
The purpose of the calculations is to find the largest out-of-balance force that must be resisted by the reinforcement in order to stabilize the slope. ReActiv allows you to calculate:
The out-of-balance force (T) for an individual mechanism
The largest out-of-balance force for the fan of mechanisms that emanates from each point on a search grid
The greatest out-of-balance force of any mechanism in the slope (the T max
mechanism) — see Chapter 7
The basal mechanism that has an out-of-balance force of zero (the T ob
mechanism) — see Chapter 7
The Mechanisms View displays the results of these calculations in a spreadsheet containing, for each mechanism:
The X- and Y- coordinate of the mechanism’s heel
The angle of the upper wedge
The out-of-balance force
Notes indicating the type of mechanism (see Chapter 7), whether the mechanism is a critical mechanism (see Chapter 7), the T max
, or the T ob
mechanism
(Optionally) The type of mechanism (see Chapter 7)
Reinforcement View
The Reinforcement View displays the reinforcement layout required to stabilize the slope.
16 ReActiv 1.7 User Manual
The suggested layout is suitable for preliminary design. The procedure for establishing a final design is discussed in Chapter 9.
For each layer of reinforcement in the suggested layout, ReActiv displays:
The name of the reinforcement
The reinforcement type (Geotextile, Geogrid, Soil Nails or User-defined)
The strength of the reinforcement
The depth of the layer
The length of the reinforcement
The reinforcement’s inclination
Notes giving special information relevant to that layer (for example, in the case of soil nails, the horizontal spacing of the nails)
Toolbar
The Toolbar provides mouse-users with quick access to commonly used menu commands.
To find out what each button does, refer to ReActiv’s help system or place the mouse pointer over each button in turn and read the tooltip (description) that appears after a short delay.
Status Bar
The Status Bar provides a summary of the key information that you will require when working in each of ReActiv’s views.
Soils
The Status Bar changes as you move from one view to another and reflects the information that you have entered into the program.
The Status Bar also provides an explanation of menu commands as you scroll through them and descriptions of what the buttons on the Toolbar do as you move the mouse pointer over them.
ReActiv implements seven types of soil:
Gravel
Sand
Chapter 3: Overview
Silt
Clay
Fill
Chalk
Custom
17
Soil Manager
ReActiv’s Soil Manager makes it easy to add, edit, and delete soils. The Soil Manager is a floating dialog box that remains on top of all other windows until you choose to close it. The Soil Manager displays the names of every soil that has been created in the current job, and provides buttons that duplicate commands on the Soil menu.
If it is not already showing, you can display the Soil Manager by:
Ticking View > Soil Manager on the Job View’s menu bar
Clicking on the Soil Manager button on the Toolbar
You can close the Soil Manager by:
Unticking View | Soil Manager on the Job View’s menu bar
Clicking on the Soil Manager button on the Toolbar
Choosing the Close command from the Soil Manager’s control menu
You can move the Soil Manager around the screen in the usual ways, by dragging its title bar with the mouse or by choosing the Move command from the Soil
Manager’s control menu and then using the appropriate cursor keys.
Soil classification system and database
ReActiv uses the information you provide about a soil’s classification to check the parameters that you enter via the Soil Properties dialog box.
ReActiv uses the Soil Classification System that was introduced in ReWaRD®, our retaining wall research and design program. The Soil Classification System provides a comprehensive and systematic description of commonly-encountered soil types and is linked to an extensive database of peak and critical state soil parameters.
In the Soil Classification System, each soil is classified according to three main descriptors:
Group
Class (depends on Group)
State (depends on Group and Class)
18 ReActiv 1.7 User Manual
Chapter 13 lists the various Groups, Classes, and States that ReActiv recognizes and compares them with established soil classification systems.
The selected soil
Although you may define the properties of more than one soil, only one soil is used by the program at any one time. This soil is known as the Selected Soil.
You may choose the Selected Soil by choosing Slope | Selected Soil... from the Job
View’s menu bar. Select one of the soils listed in the listbox and click the OK button,
ReActiv re-draws the soil column (if displayed) to reflect the soil you have selected.
Design parameters
When ReActiv performs its calculations, it uses design values of the key soil parameters rather than characteristic values. The design value of the soil’s angle of shearing resistance (N) is given by:
design
tan
1
tan
F
and the design value of the soil’s effective cohesion (cN) is given by:
c
'
design
c
'
F c
If you specify critical state parameters, ReActiv sets the partial factors in these equations to 1.0.
Slopes
ReActiv implements three types of slope:
One-part
Two-part
Infinite
Stability of upper slopes/crests
The upper slope of Two-part slopes and the sloping crest of Infinite slopes are potentially unstable when: tan
i
r u
tan
where r u
is Bishop’s pore pressure parameter, and N is the soil’s angle of shearing resistance. The angle i is given by:
For Two-part slopes, the angle of the upper slope
For Infinite slopes, the crest angle
ReActiv checks for potential instability of the upper slope or sloping crest when it validates the parameters you enter into the slope’s property box. However, even if the slope is unstable, ReActiv allows you calculate the reinforcement required to stabilize the lower slope on the assumption that you will analyse the stability of the upper slope/sloping crest as a separate exercise. If you do this using ReActiv, then
Chapter 3: Overview 19 you should treat the reinforced lower slope as a competent foundation to the upper slope/sloping crest.
Water regimes
ReActiv implements four types of water regime:
Parallel
Horizontal
Parabolic
Custom
For water regimes other than custom, ReActiv calculates Bishop’s pore pressure parameter (r u
) for you, using the formula given by Mitchell (1983), Earth structures
engineering, Allen & Unwin Inc., Boston, p128.
Parallel water regime
For parallel water regimes, Bishop’s pore pressure parameter (r u
) is given by:
r u
w
cos
2
where ( w
is the unit weight of water; ( is the unit weight of the selected soil (see page 18); and $ is the angle of the lower slope.
Horizontal water regime
For horizontal water regimes, Bishop’s pore pressure parameter (r u
) is given by:
r u
w
where ( w
and ( are defined above.
Parabolic water regime
For parabolic water regimes, Bishop’s pore pressure parameter (r u
) is given by:
r u
w
cos
where ( w
, (, and $ are defined above.
Reinforcements
ReActiv implements four types of reinforcement:
Geotextiles
Geogrids
Soil nails
Custom
Reinforcement Manager
ReActiv’s Reinforcement Manager makes it easy to add, edit, and delete
20 ReActiv 1.7 User Manual reinforcements. The Reinforcement Manager is a floating dialog box that remains on top of all other windows until you choose to close it. The Reinforcement Manager displays the names of every reinforcement that has been created in the current job.
If it is not already showing, you can display the Reinforcement Manager by:
Ticking View > Reinforcement Manager on the Job View’s menu bar
Clicking on the Reinforcement Manager button on the Toolbar
You can close the Reinforcement Manager by:
Unticking View > Reinforcement Manager on the Job View’s menu bar
Clicking on the Reinforcement Manager button on the Toolbar
Choosing the Close command from the Reinforcement Manager’s control menu
Design strength
The design strength (P des
) that you enter into ReActiv is the long-term factored design strength of the reinforcement per unit width of slope (in kN/m).
According to the Advice Note, the design strength should be derived from the
unfactored long-term characteristic strength of the reinforcement (P c set of partial safety factors as follows:
) by applying a
P design
P c
where f d
is a factor-of-safety against mechanical damage before and during installation; f e
is a factor-of-safety against environmental (chemical and biological) effects during the reinforcement’s design life; and f m
is a factor-of-safety to cover uncertainties in material strength (including extrapolation of data).
Values for P c
, f d
, f e
, and f m
may be taken from the BBA certificate or manufacturer’s literature for the reinforcement.
Further guidance is available in the CIRIA Special Publication 123, Soil reinforcement
with geotextiles, by RA Jewell (1996).
Design factors
ReActiv requires you to specify certain design factors that govern the base-sliding and pullout resistance of the reinforcement. The direct-shear factor is used in calculations which involve sliding of soil over the surface of the reinforcement, whereas the
Chapter 3: Overview 21
bearing factor is used in calculations involving local bearing failure on the ribs of geogrids or custom reinforcement.
Geotextiles
ReActiv uses the direct-shear factor to calculate the resistance that a geotextile provides against base-sliding and also — since pullout failure of a geotextile involves sliding along both its sides — its pullout resistance.
Geogrids
ReActiv uses the direct-shear factor to calculate the resistance that a geogrid provides against base-sliding.
Since pullout failure of a geogrid involves local bearing failure on the front edges of its ribs, ReActiv uses the bearing factor — and not the direct-shear factor — to calculate a geogrid’s pullout resistance.
Soil nails
ReActiv uses the direct-shear factor to calculate the resistance that soil nails provide against base-sliding and also — since pullout failure of soil nails involves sliding along their circumference — their pullout resistance.
Custom reinforcement
Since you may want to specify certain types of geogrid as custom reinforcement
(perhaps to get around ReActiv’s validation checks), ReActiv uses the bearing factor
— and not the direct-shear factor — to calculate the pullout resistance of custom reinforcement. This allows you to control the base-sliding and pullout calculations independently of each other.
Calculation options
Interwedge friction factor
The angle of friction (N
12
Chapter 9) is given by:
) that acts on the boundary between Wedges 1 and 2 (see where N is the angle of shearing resistance of the soil and f iwf
is the interwedge
friction factor. ReActiv allows you to enter interwedge friction factors between 0 and
1.
Setting f iwf
= 0 leads to conservative designs but has the advantage that the equations used to calculate the out-of-balance force can be simplified, thereby eliminating the need to decide on which wedge the reinforcement force acts (see Chapter 9 for further discussion of this point).
When you want to minimize the conservatism in your design, you can enter a nonzero value of f iwf
. The out-of-balance force then depends on which wedge the reinforcement force acts (see Chapter 9).
Setting f iwf
= 0.5 and assuming that all the reinforcement force acts on Wedge 2 provides a reasonable upper bound to results obtained using Caquot and Kerisel’s charts and other methods (see Chapter 11). The agreement is less reasonable for small slope angles.
22 ReActiv 1.7 User Manual
Project information
ReActiv allows you to store project information in each file, so that you can keep a record of the purpose and progress of your calculations.
The Project Information dialog box provides controls for entering your company’s name and address, the project description and number, the engineer’s initials, a revision letter and date, and notes about the current job.
Choose Edit > Project Info... to display the Project Information box.
Printing
ReActiv allows you to print your input and output data on a wide variety of printers and to obtain a preview of the printout on your computer screen.
The Print dialog box allows you to select various options for controlling what gets printed and where it gets printed.
You can display the Print dialog box by:
Choosing File > Print... from the menu bar
Clicking on the Print button on the
Button Bar
The currently selected printer is displayed at the top of the dialog box.
You can change the properties of the printer by choosing the Properties... button.
Print preview
ReActiv provides a print preview facility, which allows you to see what will appear on the printed page. This preview facility is extremely useful if you only want to print a part of your input or output data, since it allows you to find out on which page the required data will appear.
You can display the Print Preview window by:
Choosing File > Print Preview... from the menu bar
Clicking on the Print Preview button on the Button Bar
Chapter 3: Overview 23
Customizing the program
You can customize many of the default parameters that ReActiv provides in each dialog box, by holding down the CTRL key and then clicking on the Defaults button.
ReActiv saves the values given in the dialog box in Windows’ Registry, for later recall.
For further information, consult ReActiv’s help system.
24 ReActiv 1.7 User Manual
Chapter 4
Tutorial 1: embankment in dense sand
This chapter shows you how to determine the most critical mechanism in the slope and how to calculate the depth, length, and spacing of the reinforcement needed to stabilize that slope. The Tutorial assumes you have no prior knowledge of ReActiv, so takes you step-by-step through setting up and solving this problem.
The chapter shows you how to set up a simple project in in ReActiv, calculate the
T max
and T ob
mechanisms, determine the required reinforcement, and print the results of your calculations.
The worked example described in this chapter is identical to Example 1 in Appendix
J of the UK Highways Agency’s Advice Note (see pages J/1 to J/2). If you have a copy of the Advice Note, you may find it helpful to read the relevant pages before working through this chapter.
Embankment in dense sand
The worked example comprises an 8m high slope in dense sand, which is to be reinforced by horizontal geogrids so that it may stand at 70E to the horizontal. The sand has an angle of friction of 35E and a bulk density of 20kN/m³. These are design values rather than peak values, hence they should be used with partial safety factors of 1.0.
The reinforcement has a characteristic strength of 20kN/m but, after applying various factors-of-safety, that strength is reduced to 14.4kN/m for design purposes. There is no surcharge at the top of the slope.
The geogrid’s bearing factor ("N) is 0.95 and its interface sliding factor (") is 0.8. See sections 2.33 and 2.23 of the Advice Note for the definition of these parameters.
Note also that ReActiv uses different terms and symbols for these parameters: the bearing factor is given the symbol f symbol f b
and the interface sliding factor is given the ds
and is called the direct shear factor.
Creating a project
The instructions that follow describe how you might define this worked example in
ReActiv.
Running the program
If ReActiv is not already running, start the program as described on page 12.
ReActiv’s title screen appears and, after a few moments, is replaced by the program’s main window (the Frame Window) and the Job View, with the words “Untitled: Job
View” in its caption bar. The Job View is where you will enter the data that defines the reinforced slope you want to analyse.
Defining the soil
The first task in defining a new project is to create the soil that makes up the slope.
Creating a new soil
To create a new soil, choose Insert > Soil > Sand... from the Job View’s menu bar.
ReActiv creates the new soil and displays its property box.
Soil properties
Chapter 4: Tutorial 1: embankment in dense sand
The soil properties box is where you enter the angle of shearing resistance, effective cohesion, and bulk density of the soil. Here you will also find a button that takes you to the soil’s classification box, where you can enter the soil’s engineering description (which ReActiv uses to validate the parameters you enter).
To display the soil classification box, click on the Classification... button.
25
Classifying the soil
ReActiv includes an extensive database of soil properties which is linked to
Geocentrix’s Soil Classification System (see Chapter 13). By classifying a soil, you allow ReActiv to validate the parameters you enter for it and hence catch any errors made during data entry.
The Soil Classification box lists the relevant classes and states for the soil type you have created. In this instance, the Soil Classification box lists the various classes and states for sand, as shown below.
For this worked example, leave the sand’s class as Unclassified but set its state to Dense.
Type a name for the soil in the Name edit box (e.g. “Dense Sand”) and then click OK. You are returned to the Soil
Properties box.
Entering soil properties
Select the Critical State button. This tells ReActiv that the strength parameters that you are going to enter for this soil will be critical state (i.e. large displacement) values. The two Factor of Safety boxes are filled with the value 1 and are disabled.
Click the Defaults button. The various edit boxes are filled with default parameters for a dense sand (since that is the classification you gave this soil in the previous step). Change the soil’s angle of friction from 32 to 35E and its unit weight from
20.348kN/m³ to 20kN/m³. Leave the effective cohesion unchanged as 0kN/m².
Note also that the soil’s density changes automatically (to 2039.4kg/m³) when you change the unit weight.
Click OK to confirm the values. You are returned to the Job View. Note that several commands on the Job View’s Slope menu are now enabled.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 1\STEP1.RAV
26 ReActiv 1.7 User Manual
Defining the slope
To define the geometry of the slope, choose Insert > Slope > One-Part... from the Job View’s menu bar. The following property box appears.
Change the Lower Slope Height to
8m and the Lower Slope Angle to
70E.
Click OK to confirm the data entered. When you are returned to the Job View,
ReActiv draws the slope with a soil column on its left hand side.
The Insert > Water Regime sub-menu and Edit > Surcharge... command are now enabled. However, you still can’t use any of the commands on the Calculate menu until you have specified the reinforcement to be used.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 1\STEP2.RAV
Viewing the slope
You may want to change the scale at which the slope is drawn in the Job View, in order to see it more clearly. You can change the scale in a number of ways, by:
Choosing one of the scales on the View menu
Choosing Zoom In or Zoom Out on the View menu to change the scale to its next level up or down
Positioning the mouse pointer over one of the rulers and clicking the right mouse button. A pop-up menu appears, from which you can choose the scale you want
Clicking on the Zoom In or Zoom Out buttons on the Button Bar to change the scale to its next level up or down
For this example, the best scale is probably 1:100 (provided the Job View is maximized — if not, click on the Frame Window’s maximize button and the Job
View’s maximize button to rectify this). Position the mouse pointer over one of the rulers and click the right button. A pop-up menu appears. Choose the scale 1:100.
The slope and the soil column are re-drawn at the new scale.
Since this example does not involve a water regime or a surcharge, the next task is to define the reinforcement.
Defining the reinforcement
To define the reinforcement, choose
Insert > Reinforcement > Geogrid...
from the Job View’s menu bar. The following property box appears.
Type a name for the reinforcement
(e.g. “Geogrid 1") and change the
Design Strength to 14.4kN/m, the
Direct Shear factor to 0.8, and the
Bearing factor to 0.95. The Angle of
Inclination box is disabled.
Chapter 4: Tutorial 1: embankment in dense sand 27
Click OK to confirm the values you have entered. This time when you return to the
Job View, the commands on the Calculate menu are enabled. ReActiv now has enough information to calculate the required reinforcement.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 1\STEP3.RAV
Calculating the reinforcement
To calculate the reinforcement layers required to stabilize the slope as well as the
T max
and T ob
mechanisms, choose Calculate > Calculate All from the Job View’s menu bar or click on the Calculate All button on the Toolbar.
ReActiv performs a series of calculations that culminate in the required reinforcement being displayed in its Reinforcement View. The steps involved are:
1. The program searches for the T max
and T ob
mechanisms
2. It then calculates the required reinforcement
3. Finally, it displays the results in its three main views
ReActiv performs these steps automatically, so that you get the solution to your problem with the least possible effort and in the quickest possible time.
Reviewing the results
ReActiv draws the required reinforcement layers on top of the picture of the slope in the Job View. To bring the Job View to the front of the display, either click on it or choose the appropriate command from the Window menu (labelled Job View).
You will find it easier to study the contents of the Job View if you maximize its window.
You can also display the T max
and T mechanisms in the Job View by: ob
Selecting the appropriate commands on the Job Views’ View menu
Positioning the mouse pointer anywhere in the Job View and clicking the right mouse button. A pop-up menu appears. Click Tmax and Tob to display the T max mechanisms (respectively)
and T ob
When you have selected all these options, the Job View looks something like the screenshot shown above.
Reviewing the reinforcement layout
You can review the required reinforcement by inspecting the contents of the Reinforcement View.
To bring the Reinforcement View to the front of the display, either click on it or choose the appropriate command from the Window menu
(labelled Reinforcement View). You
28 ReActiv 1.7 User Manual will find it easier to read the contents of the Reinforcement View if you maximize its window.
According to ReActiv, the slope being analysed requires nine layers of reinforcement and, for the most efficient layout, the layers would be placed at the following depths:
Layer 1 at 1.41m
Layer 2 at 2.83m
Layer 3 at 4.00m
Layer 4 at 4.90m
Layer 5 at 5.66m
Layer 6 at 6.32m
Layer 7 at 6.93m
Layer 8 at 7.48m
Layer 9 at 8.00m
These depths are identical to those given in the Advice Note. The required length of the layers varies from 3.32m at the top to 3.39m at the bottom.
Reviewing the mechanisms
You can review the results of the searches for the T max
and T ob mechanisms by inspecting the contents of the Mechanisms View. To bring the Mechanisms View to the front of the display, either click on it or choose the appropriate command from the Window menu (labelled
Mechanisms View). You will find it easier to read the contents of the Reinforcement View if you maximize its window.
According to ReActiv, the mechanism with the largest out-of-balance force anywhere in the slope (i.e. the T max
mechanism) has the following properties:
X = 1.26m, Y = 0.00m, 2
1
= 58.3E, T = 113.52kN/m
These values are in close agreement with the results given in the Advice Note.
The critical mechanism that requires exactly zero reinforcement to be stable (i.e. the
T ob
mechanism) has the following properties:
X = 3.39m, Y = 0.00m, 2
1
= 62.5E, T = 0.00kN/m
The X-value is in close agreement with the length L
B
given in the Advice Note.
The Notes column of the Mechanisms View indicates which mechanism is which and also gives additional information about the T indicates that the T max max
mechanism. The word "Baseline"
mechanism occured along the slope’s baseline rather than in the body of the slope. Refer to the page 43 for a full explanation of these terms.
Clearing the results
Although it is automatically done when you perform a new calculation, you can clear the results of the current calculation at any time by choosing Calculate > Clear
Results... from the menu bar.
Chapter 4: Tutorial 1: embankment in dense sand 29
Printing the results
When you are happy with the results of your calculations, you will want to obtain a print-out of those results and the corresponding input data. ReActiv uses printer drivers supplied and supported by Microsoft Windows — so you should have no difficulty obtaining high-quality output from ReActiv.
ReActiv allows you to print your input and output data by choosing the File > Print... command from the menu bar. ReActiv prints the input data in the following order:
Project information
Soils
Reinforcements
Slope
Water regime
Surcharge
Options and the output data in this order:
Mechanisms
Required reinforcement
Job View picture
Controlling the printer
The Print dialog box allows you to select various options for controlling what gets printed and where it gets printed. You can display the Print dialog box by:
Choosing File | Print... from the menu bar
Clicking on the Print button on the
Button Bar
The currently selected printer is shown highlighted.
Select one of the buttons in the Page
Range panel, according to whether you want to print All the available pages or only certain Pages (as specified in the box alognside). You can find out what will be printed on each page by choosing
Print Preview from the menu bar.
Click Print when you are ready to print.
You will find a copy of the project in its final form in Windows’ Shared Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 1\TUTORIAL1.RAV
30 ReActiv 1.7 User Manual
Chapter 5
Tutorial 2: cutting in stiff clay
This chapter describes how you might go about solving a more complicated reinforced slope problem using ReActiv. It assumes that you have already been through Tutorial 1 and that you are familiar with the basic layout of ReActiv, as described in Chapter 3.
The worked example described in this chapter is identical to Example 3 in Appendix
J of the Advice Note (see pages J/5 to J/7). If you have a copy of the Advice Note, you may find it helpful to read the relevant pages before working through this chapter.
Cutting in stiff clay
The worked example comprises a 6m high cutting in stiff clay, which is to be reinforced by soil nails so that it may stand at 70E to the horizontal. The clay has an angle of shearing resistance of 20E, effective cohesion of 0kN/m², and a bulk density of 20kN/m³. The reinforcement has a design strength of 41.8kN/m after applying various factors-of-safety to it. Bishop’s pore pressure parameter for the slope (r u
0.15. There is no surcharge at the top of the slope.
) is
The 16mm diameter soil nails are inclined at 10E to the horizontal, and are spaced at 1m intervals horizontally. The holes into which they are installed and grouted are
150mm in diameter. The nails’ interface sliding factor (") is 0.9. See section 2.23 of the Advice Note for the definition of this parameters, which in ReActiv is given the symbol f ds
and is called the direct shear factor.
Creating the document
The instructions that follow describe how you might define Worked this worked example in ReActiv.
Running the program
If ReActiv is not already running, start the program as described on page 12.
ReActiv’s title screen appears and, after a few moments, is replaced by the program’s main window, its Frame Window.
Creating a new project
To create a new project, choose File > New from the program’s menu bar or click on the File New button on the menu bar. Answer No to the question about saving the current document (unless you want to save it, in which case answer Yes).
When you do this, ReActiv creates a new window with the words "Untitled: Job
View" in its caption bar. This is the new project’s Job View, where you will enter the data that defines the reinforced slope that you want to analyse.
Defining soil properties
The first task in defining the new project is to create the soil that defines the properties of the slope.
Using the Soil Manager
In this worked example, you will create the new soil using
ReActiv’s Soil Manager. To display the Soil Manager, tick View
> Soil Manager on the Job View’s menu bar or click on the
Chapter 5: Tutorial 2: cutting in stiff clay appropriate Soil Manager button on the Toolbar. The Soil Manager appears.
31
Creating the new soil
To create a new soil from the Soil
Manager, click the New button. A dialog box appears.
Select Clay and click OK (or doubleclick on Clay). ReActiv creates the new soil and then displays the Soil
Properties dialog box.
Click on the Classification... button to display the soil’s classification box.
Classifying the soil
The Soil Classification box lists the relevant classes and states for the soil type you have created. In this instance, the box lists the various classes and states for clay, as shown below.
For this worked example, leave the clay’s class as Unclassified but set its state to Stiff.
Type a name for the soil in the Name edit box (e.g. “Stiff Clay”) and then click OK. You are returned to the Soil Properties box.
Entering soil properties
The Soil Properties box is where you enter the angle of shearing resistance, effective cohesion, and bulk density of the soil.
Select the Critical State button. This tells ReActiv that the strength parameters that you are going to enter for this soil will be critical state (i.e. large displacement) values. The two Factor of Safety boxes are filled with the value 1 and are disabled.
Click the Defaults button. The various edit boxes are filled with default parameters for a stiff clay (since that is the classification you gave this soil in the previous step).
Change the soil’s effective cohesion from 2 to 0kN/m² and its unit weight from
20.103kN/m³ to 20kN/m³.
Click OK to confirm the values. You are returned to the Soil Manager, which now displays the name of the newly created soil. Close the Soil Manager by unticking
View > Soil Manager on the Job’s View menu bar. Your next task is to define the slope.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 2\STEP1.RAV
Defining the slope
To define the slope, choose Insert > Slope > One-part... from the Job View’s menu
32 ReActiv 1.7 User Manual bar or click on the Slope button on the Toolbar. A dialog box appears.
Change the Lower Slope Height to 6m and the Lower Slope Angle to 70E.
Click OK to confirm the data entered into the Slope box. This time, when you are returned to the Job View, ReActiv draws the slope and (provided the option is set on the View menu) displays a soil column on the left hand side of the slope.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 2\STEP2.RAV
Viewing the slope
For this example, the best scale is probably 1:100 (provided the Job View is maximized — if not, maximize the Job View). Position the mouse pointer over one of the rulers and click the right button. A pop-up menu appears. Choose the scale
1:100. The slope and the soil column are re-drawn at the new scale.
The next task is to define the water regime.
Defining the water regime
To define the water regime, choose
Insert > Water Regime > Custom...
from the Job View’s menu bar. The following dialog box appears.
Change Ru to 0.15 and click OK to confirm the data entered. When you are returned to the Job View, ReActiv displays the r u slope.
value underneath the
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 2\STEP3.RAV
Since this worked example does not involve a surcharge, the next task is to define the reinforcement.
Defining the reinforcement
Using the Reinforcement Manager
In this worked example, you will create the reinforcement using
ReActiv’s Reinforcement Manager. To display the Manager, tick View > Reinforcement Manager on the Job Views’ menu bar or click on the Reinforcement Manager button on the
Toolbar. The Reinforcement Manager appears.
Creating the new reinforcement
To create a new reinforcement from the Reinforcement
Manager, click the New button. A dialog box appears.
Chapter 5: Tutorial 2: cutting in stiff clay 33
Select Soil Nails from the list and click OK to confirm. The following dialog box appears.
The Reinforcement box is where you specify the properties of the reinforcement. Type a name for the reinforcement (e.g. “Soil Nail”) and change the Design Strength to
41.8kN/m, the Angle of Inclination to
10E, the Hole Diameter to 150mm, the Horizontal Spacing to 1000mm, the Direct Shear factor to 0.9.
Click OK to confirm the values you have entered. You are returned to the
Reinforcement Manager, which now displays the name of the newly created reinforcement. Close the Manager by clicking on the appropriate Reinforcement
Manager button on the Toolbar.
This time when you return to the Job View, the commands on the Calculate menu are enabled. ReActiv now has enough information to calculate the required reinforcement.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 2\STEP4.RAV
Calculating the reinforcement
In this worked example, you will calculate the required reinforcement manually, stepby-step, rather than use ReActiv’s automatic calculation feature. The steps involved in calculating the required reinforcement are:
First, search for the T max
mechanism
Second, search for the T ob
mechanism
Finally, calculate the required reinforcement
Searching for the T
max
mechanism
To search for the T menu bar.
max
mechanism, choose Calculate > Tmax from the Job View’s
ReActiv performs two separate searches:
The first for the mechanism with the greatest out-of-balance force anywhere in the body of the slope
The second for the mechanism with the greatest out-of-balance force anywhere along the baseline of the slope
ReActiv keeps you fully informed as to the progress of these calculations and, when it has finished, displays a dialog box giving you the more critical of the two mechanisms that it has found in its searches.
These values differ from the results given in the Advice
Note, because by default ReActiv applies all the reinforcement force to Wedge 2 (the lower wedge),
34 ReActiv 1.7 User Manual whereas in the Advice Note the reinforcement force is applied to Wedge 1 (the upper wedge).
To reproduce the results given in the Advice Note, first click on the OK button to return to the Mechanisms View and then choose Options > Tension On Wedge 1 from the Mechanisms View’s menu bar or click on the Tension on Wedge 1 button on the Toolbar. The following message box appears:
Click Yes to proceed and then repeat the calculation of T max
, by choosing Calculate
> Tmax from the menu bar. When it has completed the calculation, ReActiv displays a dialog box giving you the new result:
X = 1.54m
Y = –0.27m
2
1
= 59.2E
T = 207.90kN/m
These values are in close agreement with the results given in the Advice Note.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 2\STEP5.RAV
Searching for the T
ob
mechanism
To search for the T ob
mechanism, choose Calculate > Tob from the Job View’s menu bar. ReActiv performs two separate searches:
The first for the mechanism with the greatest out-of-balance force anywhere along the baseline of the slope
The second for the baseline mechanism that has an out-of-balance force of exactly zero
The result of the first search is used as a "seed" for the start of the second search.
ReActiv keeps you informed as to the progress of these calculations and, when it has finished, displays a dialog box giving you the result of its search for T ob
.
The X-value is the same as the length L
B
given in the
Advice Note.
When you click the OK button, you are returned to the
Mechanisms View, which displays the result of the calculation.
Calculating the required reinforcement
Now that you have calculated T max
and T ob
, you can proceed to calculate the required reinforcement. To do so, choose Calculate > Reinforcement from the menu
Chapter 5: Tutorial 2: cutting in stiff clay 35 bar or click on the Calculate Reinforcement button on the Toolbar.
ReActiv creates the Reinforcement View and then uses the results of the T max
and T ob calculations to determine the required number of reinforcement layers and their optimum spacing. It then displays the required reinforcement in the Reinforcement
View.
According to ReActiv, the slope being analysed requires six layers of reinforcement and, for the most efficient layout, the layers would be placed at the following depths:
Layer 1 at 1.34m
Layer 2 at 2.68m
Layer 3 at 3.79m
Layer 4 at 4.65m
Layer 5 at 5.37m
Layer 6 at 6.00m
The length of the first layer of reinforcement is 10.05m.
Reducing the nail lengths
The Advice Note describes a method of reducing the required length of soil nails by reducing the horizontal spacing of the first row of nails and determining the layout of the other layers based on the length of the second row. A discussion of this is given in paragraphs 4.20-4.22 of the Advice Note.
To take advantage of this alternative method of calculating the required reinforcement, choose Options > Reduce Nail Lengths from the menu bar. Then choose Calculate > Calculate All to re-calculate the required reinforcement based on the alternative method and display the results in the Reinforcement View.
According to ReActiv, the length of the top row of soil nails may be reduced to
8.36m (a saving of 1.69m) provided its horizontal spacing is reduced to 775mm. The lengths of the other layers of reinforcement are reduced as well.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 2\STEP6.RAV
Visualizing the layout
You can view the calculated reinforcement layers in the Job View as well as the
Reinforcement View. To bring the Job View to the front of the display, either click on it or choose the appropriate command from the Window menu (labelled Job
View).
You can also display the T max
and T ob
mechanisms in the Job View by selecting the appropriate commands on the View menu.
When you have selected all these options, the Job View looks something like this:
36 ReActiv 1.7 User Manual
You will find a copy of the project in its final form in Windows’ Shared Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 2\TUTORIAL2.RAV
Chapter 6: Tutorial 3: fixed vertical spacings 37
Chapter 6
Tutorial 3: fixed vertical spacings
This chapter shows you how to optimize your reinforced slope designs using
ReActiv. It assumes that you have already been through tutorials 1 and 2 (as described in Chapters 4 and 5).
The worked example described in this chapter uses reinforcement layers at a fixed vertical spacing to reinforce a two-part slope. First, a library of available reinforcement is entered into the program and then ReActiv is left to choose which reinforcement to use at each depth in the slope.
Fixed vertical spacings
The worked example comprises a 9.5 m high slope in sand, which will be reinforced by horizontal geogrids. The lower part of the slope has an inclination of 70E and height of 8m, while the upper part has an inclination of 15E and height of 1.5m. The sand has an angle of shearing resistance of 32E, zero effective cohesion, and a bulk density of 20kN/m³. These parameters are critical state values and hence should be used with partial safety factors of 1. Bishop’s pore pressure parameter for the slope
(r u
) is 0.15. There is a 10kPa surcharge at the top of the slope.
Five different types of geogrid are available with the following strengths: 1, 16, 24,
32, and 40 kN/m. The geogrids will be placed at a constant vertical spacing of
600mm. The geogrids’ bearing factors and direct shear factors are all 0.8. The interwedge friction factor is 0.25.
Creating the project
The instructions that follow describe how you use ReActiv’s fixed vertical spacing feature. The tutorial illustrates various short-cuts that can be used to speed up your use of the program.
Running the program
If ReActiv is not already running, start the program as described on page 12.
ReActiv’s title screen appears and, after a few moments, is replaced by the program’s main window, its Frame Window.
Creating a new project
To create a new project, click on the New button on the Toolbar. Answer No to the question about saving the current document (unless you want to save it, in which case answer Yes).
Defining soil properties
The first task is to create the soil that forms the two-part slope.
In this worked example, you will create the new soil through the pull-down menus.
Choose Insert > Soil > Sand... from the Job View’s menu bar.
Type a name for the soil in the Name edit box (e.g. “Sand”). Select the Critical State button and enter the remaining properties as follows: angle of friction = 32E, effective cohesion = 0kPa, and unit weight = 20kN/m³. Do not change the soil’s classification (since it is unspecified). Click OK to confirm the values.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
38 ReActiv 1.7 User Manual
GEOCENTRIX\REACTIV\1.7\TUTORIAL 3\STEP1.RAV
Defining the slope
To define the slope, choose Insert >
Slope > Two-part... from the Job
View’s menu bar.
Change the Upper Slope Height to
1.5m but leave the Upper Slope
Angle at 15E. Change the Lower
Slope Height to 8m and the Lower
Slope Angle to 70E. Click OK to confirm the data entered.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 3\STEP2.RAV
Defining the water regime
To define the water regime, choose
Insert > Water Regime > Custom...
from the Job View’s menu bar.
Change Ru to 0.15 and click OK to confirm the data entered.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 3\STEP3.RAV
Defining the surcharge
To define the surcharge, choose Edit
> Surcharge... from the Job View’s menu bar.
Enter 10kPa into the dialog box that appears and click OK to confirm the data entered.
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 3\STEP4.RAV
Defining the reinforcement
Using the Reinforcement Manager
In this worked example, the best way to create the available reinforcements is to use
ReActiv’s Reinforcement Manager, which you can display by ticking View >
Reinforcement Manager on the Job View’s menu bar.
Creating the new reinforcement
Chapter 6: Tutorial 3: fixed vertical spacings
To create a new reinforcement from the Reinforcement
Manager, click the New... button and select Geogrid in the list that appears. Click OK to create the reinforcement.
39
In the dialog box that appears, type a name for the reinforcement (e.g. “Topgrid 1") and change its Design
Strength to 1kN/m. Leave the Direct Shear and
Bearing factors as 0.8. Click OK to confirm the values you have entered.
Repeat the instructions given above to create the remaining reinforcement types, but enter the following names and strengths (keeping the direct shear and bearing factors all equal to
0.8):
Topgrid 2, 10kN/m
Topgrid 3, 24kN/m
Topgrid 4, 32kN/m
Topgrid 5, 40kN/m
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 3\STEP5.RAV
Calculating the reinforcement layers
Setting the calculation options
Before asking ReActiv to calculate the reinforcement layout, you need to set the appropriate options for this worked example:
Select the fixed vertical spacing option
Select which reinforcements to use
Enter the magnitude of the vertical spacing
Enter the value of the interwedge friction factor
To obtain the appropriate calculation, select the Fixed Vertical Spacing option from the Options menu or click on the Fixed Vertical Spacing button on the Toolbar.
N e x t , c h o o s e O p t i o n s >
Reinforcement Used... from the menu bar.
Select Geogrid in the Reinforcement
Type box and then tick all five
“Topgrids” in the Use this/these
reinforcement(s) box. Change the
Vertical Spacing to 600mm and click
OK to confirm the data entered.
Finally, change the Interwedge
Friction Factor by choosing Options >
Interwedge Friction.... Enter 0.25 and click OK to confirm the data entered.
40 ReActiv 1.7 User Manual
You will find a copy of the project in its current form in Windows’ Shared
Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 3\STEP6.RAV
You are now ready to perform the calculation.
Performing the calculation
To perform the required calculations, simply choose the Calculate > Calculate All command from the menu bar or click on the Calculate All button on the Toolbar.
Then choose Window > Tile to display the results in three adjacent windows, as follows:
Note how the program has chosen the weakest reinforcement that provides sufficient strength at each depth to support the slope. If none of the reinforcements you had selected to use had been strong enough, the program would have reported this fact.
You will find a copy of the project in its finals form in Windows’ Shared Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\TUTORIAL 3\TUTORIAL3.RAV
Chapter 7: Calculating mechanisms 41
Chapter 7
Calculating mechanisms
ReActiv performs calculations based on limit equilibrium analysis of the two-part wedge mechanism described in Chapter 9.
ReActiv allows you to calculate the out-of-balance force for a single mechanism or for a series of mechanisms set out on a grid. The program will also search automatically for the mechanism that has the largest out-of-balance force (the T max mechanism) and the basal mechanism that has a zero out-of-balance force (the T ob mechanism). ReActiv uses these two mechanisms to determine the reinforcement required to stabilize the slope (see Chapter 8).
The results of the calculations are displayed in the Mechanisms View, where they can be inspected.
Mechanisms View
ReActiv displays the results of any stability calculations that you ask it to perform in its Mechanisms View. This View is automatically created when you choose any of the available options on the Calculate menu.
The Mechanisms View displays the results of the calculations in a spreadsheet containing, for each mechanism:
The X- and Y- coordinate of the mechanism’s heel
The angle of the upper wedge (2
1
)
The out-of-balance force or tension
Notes indicating whether the mechanism is a critical mechanism, the T max mechanism, or the T ob
mechanism
(Optionally) The mechanism’s type (defined below)
Mechanism types
A mechanism’s type depends on the positions of:
The outcrop of Wedge 1
42 ReActiv 1.7 User Manual
The interwedge boundary
There are four possible mechanisms, as indicated in the following table.
Mechanism type Wedge 1 outcrops at...
Standard
Crest or upper slope
Interwedge boundary outcrops at...
Lower slope
Narrow
Wide
Lower slope
Crest or upper slope
Lower slope
Upper slope
Extra-wide
Crest
The following diagrams illustrate the various mechanism types:
Crest
Distribution of reinforcement force
As discussed in Chapter 8, ReActiv provides two methods of calculating the reinforcement force required to stabilize a mechanism. In the first method, it is assumed that the reinforcement force acts solely on Wedge 1; and, in the second method, it is assumed that the reinforcement force acts solely on Wedge 2.
You specify which method you want to use by selecting the appropriate options on the Options menu:
Chapter 7: Calculating mechanisms 43
Tension on Wedge 1 selects the calculation method in which the reinforcement force acts solely on Wedge 1
Tension on Wedge 2 selects the calculation method in which the reinforcement force acts solely on Wedge 2
When you display the Options menu, a tick mark is shown next to the currently selected option. By default, ReActiv puts all the reinforcement force on Wedge 2.
The assumption made about where the reinforcement force acts is irrelevant when the reinforcement is horizontal (* = 0) and its interwedge friction factor (f iwf since the value of zeta (.) given in Chapter 9 is always equal to one.
) is zero,
In all other cases, however, it is necessary to choose between the two methods provided. For most practical cases, it is reasonable to assume that the reinforcement force acts on Wedge 2 (although this may not be so for small slope angles when the interwedge factor is > 0 — see Chapter 9).
It can be shown for inclined reinforcement that placing all the reinforcement force on Wedge 1 is always conservative. (Note that the design charts given in Table 4.1
of the Advice Note are based on this assumption.) However, applying all the reinforcement force on Wedge 1 can be unnecessarily conservative for steeply inclined soil nails (e.g. with angles of inclination > 10E). As discussed in Chapter 9, the alternative assumption that all the reinforcement force acts on Wedge 2 gives reasonable design results provided the interwedge friction factor is less than or equal to 0.5 and, for this reason, by default the program assumes all the reinforcement force acts on Wedge 2.
Baseline
The baseline is a line that passes through the toe of the slope at an angle * to the horizontal (where * is the angle of inclination of the reinforcement, measured anticlockwise). For geogrids and geotextiles, * is always zero; for soil nails and Userdefined reinforcement, * may be greater than or equal to zero.
Invalid mechanisms
Invalid mechanisms are those whose:
Heel position (X, Y) is outside the slope
Heel position is below the lowest layer of reinforcements (i.e. the baseline, defined below)
Upper angle (2
1
90E – *
) is less than or equal to its lower angle (2
2
) or greater than
ReActiv displays the following error message if you attempt to calculate the out-ofbalance force for an invalid mechanism.
Calculating single mechanisms
You can calculate the out-of-balance force (T) for a single mechanism by choosing Calculate
> Single Mechanism... from the menu bar. If it has not already done so, ReActiv creates the
Mechanisms Window and then displays the dialog box shown.
The Single Mechanism box is a floating dialog box that allows you to calculate the out-of-
44 ReActiv 1.7 User Manual balance force for a single mechanism. You specify the X- and Y-coordinates of the mechanism’s heel and the angle that the upper wedge (Wedge 1) makes to the horizontal (2
1
) by entering appropriate values into the X, Y, and Angle edit boxes.
When you choose the Calc button, ReActiv first of all checks whether the specified mechanism is valid (see below) and — if it is — then:
Calculates the out-of-balance force for that mechanism (which could be positive or negative)
Appends the result of the calculation to the list of mechanisms displayed in the
Mechanisms View
Calculating grid mechanisms
You can calculate the out-of-balance force (T) for a series of mechanisms by choosing Calculate > Grid
Mechanisms... from the menu bar. If it has not already done so, ReActiv creates the Mechanisms View and then displays the dialog box shown.
The Grid Mechanisms box allows you to specify a series of uniformly spaced gridlines, along which the program will perform successive calculations in order to find the critical mechanism (see page 46) at each intersection point on the grid. Only the critical mechanism for each grid point is displayed in the Mechanisms
View.
You do not need to use ReActiv’s grid feature in order to find the T max
or T ob mechanisms, since these are calculated for you automatically when you choose
Calculate > Tmax or Calculate > Tob from the menu bar.
When you choose the Calc button, ReActiv does the following:
Displays a dialog box which keeps you informed as to the progress of the calculations
Performs a search for the most critical mechanism at each intersection point on the grid and (when it has found it) displays that mechanism in the Mechanisms
Chapter 7: Calculating mechanisms 45
View
Updates the progress bar as each critical mechanism is found
Allows you to cancel the remaining calculations by choosing the Cancel button
Removes the dialogue box once all the calculations have been performed
Minimum and maximum co-ordinates
The starting and ending co-ordinates of the horizontal and vertical gridlines are given in their respective Minimum and Maximum boxes. To alter the given values:
Turn off the check mark in the Automatic box
Enter your own values in the Minimum and Maximum boxes
To restore the original values in the Minimum and Maximum boxes:
Turn on the check mark in the Automatic box
Number of lines
The number of gridlines in the horizontal and vertical directions are given in their respective No of Lines boxes. To alter the given values:
Turn off the check mark in the Automatic box
Enter your own values in the No of Lines boxes
To restore the original values in the No of Lines boxes:
Turn on the check mark in the Automatic box
When the number of gridlines in any direction is one, its maximum co-ordinate is reset to its minimum, its Maximum box is disabled, and its Spacing box is hidden.
Spacing
ReActiv automatically calculates the spacing of the gridlines in each direction from the appropriate minimum and maximum co-ordinates and number of lines. The spacing is calculated from:
Spacing
1
Automatic grid
When the Automatic box is checked, ReActiv selects the most suitable grid for multiple calculations by setting the grid co-ordinates and number of lines as follows:
For the horizontal gridlines:
Minimum co-ordinate = breadth of lower slope times the tangent of the reinforcement’s angle of inclination
Maximum co-ordinate = height of slope / 2
No of lines = 11
For the vertical gridlines:
Minimum co-ordinate = 0m
Maximum co-ordinate = breadth of lower slope (i.e. H/tan $)
No of lines = 11
46 ReActiv 1.7 User Manual
Default grid
When you choose the Default button in the Grid Mechanisms box, ReActiv puts the following default parameters in the appropriate edit boxes.
For the horizontal gridlines:
Minimum co-ordinate = R y min
times H
Maximum co-ordinate = R y max
times H where H is the total height of the slope (to its crest).
For the vertical gridlines:
Minimum co-ordinate = R x min
times B
Maximum = R x max
times B where B is the breadth of the slope.
The various min. and max. ratios are taken from Window’s Registry. If you don’t override the factory-supplied defaults, ReActiv uses the following values:
R
R min
= 0 y max
= 0.5
R
R x y min
= 0 x max
= 1.0
Critical mechanisms
For each point on the grid there is a fan of mechanisms, each with a different upper wedge angle (2
1
) and out-of-balance force (T). The critical mechanism is the one that has the largest value of out-of-balance force (where MT/M2
1
= 0).
Search algorithm
ReActiv searches for the critical mechanism within each fan using a variant of the
Golden Section Search algorithm, known as Brent’s Method. Brent’s Method uses a technique called inverse parabolic interpolation to find the minimum (or maximum) of a one-dimensional function. A full description of the method is given by Press et
al. (1992), Numerical recipes in C (2nd edition), Cambridge University Press, pp397-
402.
ReActiv indicates those mechanisms which are critical mechanisms by displaying the word "Critical" in the Notes column of the Mechanisms View.
Chapter 7: Calculating mechanisms 47
Calculating the T
max
mechanism
You can find the largest out-of-balance force (T max
) of any mechanism in the slope by choosing Calculate > Tmax from the menu bar. If it has not already done so, ReActiv creates the Mechanisms View and then begins searching for the T max
mechanism.
Searching for T
max
The steps that ReActiv follows in searching for the T max
mechanism are as follows:
First, ReActiv displays a dialog box that keeps you informed about the progress of the calculations (the number displayed in the progress bar is the number of X,
Y co-ordinates that have been considered in the search)
Second, ReActiv performs a search for the critical mechanism (see page 46) that has the largest out-of-balance force anywhere in the slope (you can cancel the search for T max
at any time by choosing the Cancel button in the dialog box)
Third, ReActiv repeats the search from a new starting point, in order to ensure that its has not accidentally picked up a local maximum
Fourth, ReActiv searches along the baseline for the mechanism with the largest out-of-balance force
Fifth, ReActiv compares the body mechanism with the baseline mechanism, and sets the T max
mechanism to be the one with the larger out-of-balance force.
Finally, ReActiv displays the result in a dialog box.
When you click the OK button, ReActiv dismisses this box and adds the T max
mechanism to the Mechanisms
View. ReActiv marks the T max
mechanism with the word
"Tmax" in the Notes column of the Mechanisms View.
Search algorithms
The search for T max
in the body of the slope is performed using the Downhill Simplex
Method to find the minimum/ maximum of a two-dimensional function. A full description of the method is given by Press et al. (1992), Numerical recipes in C (2nd
edition), Cambridge University Press, pp408-412.
The search for T max
(see page 46).
along the baseline of the slope is performed using Brent’s Method
Calculating the T
ob
mechanism
You can find the critical baseline mechanism that requires precisely zero reinforcement force to establish its equilibrium (i.e. the T ob
mechanism) by choosing
Calculate > Tob from the menu bar. If it has not already done so, ReActiv creates the
Mechanisms View and then begins searching for the T ob
mechanism.
Searching for T
ob
The steps that ReActiv follows in searching for the T ob
mechanism are as follows:
First, ReActiv searches along the baseline for the mechanism with the largest outof-balance force
Second, ReActiv searches outwards from this point along the baseline for the critical mechanism that has zero out-of-balance force
When it has found the T ob the result in a dialog box.
mechanism, ReActiv displays
When you choose the OK button, ReActiv dismisses this
48 ReActiv 1.7 User Manual box and adds the T ob
mechanism to the Mechanisms View. ReActiv marks the T mechanism with the word "Tob" in the Notes column of the Mechanisms View.
ob
Search algorithm
ReActiv searches for the T ob
mechanism using the method due to van Wijngaarden
et al., as improved by Brent. A full description of the method is given by Press et al.
(1992), Numerical recipes in C (2nd edition), Cambridge University Press, pp359-362.
The baseline T max
mechanism is used in the initial bracketing of T ob to search for the baseline T max
first.
, hence the need
Chapter 8: Calculating the required reinforcement 49
Chapter 8
Calculating the required reinforcement
ReActiv determines the reinforcement required to stabilize a given slope based on the results of the T max
and T ob
calculations described in Chapter 7.
ReActiv allows you to calculate the number of reinforcement layers required, their optimum spacing, and their length. ReActiv also allows you to save on reinforcement when using soil nails by decreasing the horizontal spacing of the top row of nails.
You can also choose to provide an extra layer of reinforcement at the top of the slope, set a fixed vertical spacing between the layers of reinforcement or change the wedge on which the tension is applied.
The required reinforcement layers are listed in the Reinforcement View and displayed on the slope in the Job View.
Reinforcement View
ReActiv displays the required reinforcement layout in its Reinforcement View. This
View is automatically created when you choose Calculate > Reinforcement from the menu bar.
The Reinforcement View displays the required reinforcement in a spreadsheet and gives, for each layer:
The name of the reinforcement
Its type
Its strength
The depth of the layer
Its length
Its inclination to the horizontal
Notes giving special information relevant to that layer (for example, in the case of soil nails, their horizontal spacing)
Calculating the required reinforcement
When you choose the Calculate > Reinforcement command, ReActiv performs a number of calculations that culminate in the required reinforcement being displayed in the Reinforcement View. These calculations are described in full in Chapter 9 but,
50 ReActiv 1.7 User Manual for convenience, are summarized below.
First, a search is made for the T max
mechanism (if it has not already been found)
Second, a search is made for the T ob
mechanism (if it has not already been found)
Third, the total number of reinforcement layers (n) is calculated
Fourth, the depth to the first layer of reinforcement (z
1
Fifth, the pullout length of the first layer (L e1
Sixth, the depths of the remaining layers are calculated
Finally, the lengths of these layers are calculated
) is calculated
) is calculated
Minimizing the length of soil nails
The Advice Note describes a method of reducing the length of soil nails by decreasing the horizontal spacing of the first layer of nails and adjusting the length of the other layers accordingly. The method is described in Chapter 9.
To minimize the length of soil nails, choose the Reduce Nail Lengths option from the
Options menu in the Reinforcement View or click on the Reduce Nail Lengths button on the Toolbar. ReActiv will then automatically reduce the horizontal spacing of the top layer of nails when you next calculate the reinforcement. The actual spacing adopted in the calculations is displayed in the Notes column of the
Reinforcement View.
Providing an additional layer at the top of the slope
When ReActiv optimizes the depths of the reinforcement layers, it places the first layer of reinforcement at some depth below the top of the slope. Because of this, there is the potential, particularly for Two-part or Infinite slopes, for the soil above the first layer to be unstable. This instability can be avoided:
In the case of geotextiles and geogrids, by providing a "wrap-around" front face
In the case of soil nails, by providing a mesh and shotcrete front face
In the absence of measures such as these to support the soil above the first layer, it may be necessary to provide an extra layer of reinforcement at the top of the slope.
You can instruct ReActiv to provide this extra layer of reinforcement by selecting the
Extra Layer At Top command from the Reinforcement View’s Options menu or by clicking on the Extra Layer At Top button on the Toolbar. A tick mark is displayed next to this option when it is selected.
ReActiv asks you whether you want to provide an extra layer at the top of the slope whenever both of the following conditions are met:
The angle between the reinforcement and the upper slope of crest is greater than or equal to 10E
The Extra Layer At Top option is not already selected Reinforcement View
Setting a the vertical spacing between the layers
When HA68/94 is selected on the Options menu, ReActiv calculates the vertical spacing between reinforcement layers according to the optimised procedure given in HA68 (see Chapter 9).
When the Fixed Vertical Spacing option is chosen on the Options menu, ReActiv places the layers at a fixed spacing (which you specify), but allows more than one strength of reinforcement to be used. At each depth, the program automatically selects the weakest layer that it can use to provide stability. The reinforcement layers that the program uses and the spacing between them can be set via the
Chapter 8: Calculating the required reinforcement
Reinforcement Used... command on the Options menu.
51
Tension on Wedge 1 or 2
ReActiv automatically specifies Wedge 2 as the wedge on which the tensions are to be applied. However, the program allows you to change it if you wish to.
To change the wedge on which the tensions are applied, choose the Tension on
Wedge 1 option or the Tension on Wedge 2 option from the Options menu in the
Menu bar; alternatively, click on the Tension on Wedge 1 button or on the Tension
on Wedge 2 button on the Toolbar.
52 ReActiv 1.7 User Manual
Chapter 9
Background theory and assumptions
The UK Highways Agency’s (HA’s) Advice Note Design methods for the
reinforcement of highway slopes by reinforced soil and soil nailing techniques
(hereinafter called the Advice Note) describes a simple design method for the preliminary assessment of reinforcement requirements for highway slopes, using either reinforced soil or soil nailing techniques.
ReActiv follows this design method step-by-step, and is intended to fully compliment the Advice Note. However, the User Manual is also designed as a stand-alone document, so that it is not necessary to refer to the Advice Note to use the program.
The theory behind ReActiv is, in some places, more advanced than that in the Advice
Note.
This chapter gives a brief résumé of the basic theory and assumptions behind the design method used by ReActiv. The design is carried out in terms of effective stresses and applies to the long-term condition of permanent works. In some cases the notation adopted in this User Manual differs from that used in the Advice Note.
A translation table of the terms that are different is given at the end of the chapter.
Two-part wedge mechanism with horizontal reinforcement
The design method used by ReActiv is based on limiting equilibrium of a two-part wedge mechanism (as shown below).
The mechanism considered has a vertical interwedge boundary. When there is no friction on the interwedge boundary, it provides inherently conservative solutions combined with reasonable simplicity, and is particularly suitable to reinforced soil geometries.
The inherent conservatism of the method can be reduced by taking interwedge friction into account. Guidance is given on this later in this chapter. Guidance is also given on the assumptions behind the method’s simplified reinforcement distribution.
The design method assumes that a competent bearing material (which is significantly stronger than the slope fill) exists beneath the retained slope. The two-part wedge mechanism is constrained to pass through the toe of the slope.
ReActiv may be used as an automatic design tool or as a calculator. When used as a design tool, the program automatically and rapidly leads you to an optimized reinforcement layout for the given slope geometry, soil parameters, water regime, reinforcement type, etc. You do not have to guess a reinforcement layout or perform trial-and-error calculations (although you may do so, if you so wish).
Chapter 9: Background theory and assumptions 53
Factors-of-safety
ReActiv employs partial factors-of-safety, along the lines given in the Advice Note.
The reinforcement strength that is entered into the program is assumed to be a
design value (i.e. already factored).
You can enter soil strength parameters either as design values (i.e. critical state or large displacement values) or as peak values. When you specify strength parameters in terms of peak values, the program requires you to enter the partial factors-of-safety that should be applied to these peak values before using them for design.
Governing equations
The following diagram defines the forces acting on the two-part wedge mechanism when horizontal reinforcement is used.
The various symbols on this diagram have the following meanings:
W i
NN i
U
RN i
is the weight of Wedge i
is the force due to effective earth pressures acting on the base of Wedge i
is the force due to water pressures acting on the base of Wedge i
is the force due to friction along the base of Wedge i
K i i
is the force due to effective cohesion along the base of Wedge i
12
is the force due to effective earth pressures on the interwedge boundary
is the force due to water pressures on the interwedge boundary
U
12
T i
12
is the force due to friction along the interwedge boundary
is the reinforcement force provided through the base of Wedge i
T
12
is the reinforcement force transferred through the interwedge boundary
The expression for the out-of-balance horizontal reinforcement force (T) required for equilibrium is:
T
T
1
T
2
The value of T can be derived from the expressions given in Appendix A of the
Advice Note.
Equations with zero interwedge friction
If it is assumed that there is no friction on the interwedge boundary (i.e. RN
12 equation for T is given by:
= 0), the
54 ReActiv 1.7 User Manual
T
W
1
tan
1
tan
1
U
1
tan
cos
1
K
1
W
2
tan
2
s
tan
s
1
U
2
s
tan
2 tan
tan
cos
2
K
2
The symbols in this equation that are not defined above are as follows:
N is the angle of friction of the soil
2
8 s i
is the angle that the base of Wedge i makes to the horizontal
is a sliding factor (see below)
The sliding factor (8 s
) depends on the properties of the reinforcement and, in particular, on how much of the sliding surface the reinforcement occupies.
Equations with interwedge friction
If it is assumed that friction acts on the interwedge boundary (i.e. RN
12
… 0), then the general equation for T is not determinate unless an assumption is made regarding the relative magnitudes of T
1
, T
2
, and T
12
.
The simplest option is to adopt one or other of the following assumptions:
All the reinforcement force acts on Wedge 1 (in which case T
12
= T
2
All the reinforcement force acts on Wedge 2 (in which case T
12
= T
1
)
)
In both cases, the equation for T is:
T
n
W
1
tan
1
tan
1
U
1
tan cos
1
K
1
U
12
1
tan
1
tan
tan
12
n
W
2
tan
2
s
tan
s
1
s
tan
2 tan
U
2 tan cos
tan
2
K
2
U
12
1
s
tan
2 tan
2
s
tan
tan
12
where N
12
is the angle of interwedge friction and .
n
(zeta) is given below. The subscript n (= 1 or 2) denotes which wedge the reinforcement force acts on.
.
1
or .
2
?
The assumption that the reinforcement force is carried solely by Wedge 1 (i.e. using
.
1
) leads to overly conservative designs for horizontal reinforcement.
The formula for .
1
is:
Chapter 9: Background theory and assumptions
1
sin cos
1
1
cos
1 tan
tan
12
55
The alternative assumption, that the reinforcement force is carried solely by Wedge
2 (i.e. using .
2
), leads to less conservative but more reasonable designs.
The formula for .
2
is:
2
sin
2
s
cos
2 tan
cos
2
s
sin
2 tan
tan
12
Interwedge friction angle
The value of .
n
depends on what angle of friction (N interwedge boundary. When N of-balance force (T max
12
= 0, .
n
12
) is assumed to act along the
= 1. Appendix A of the Advice Note describes the results of a parametric study of the effects of N
12
on the maximum out-
) for slopes inclined at angles ($) between 40 and 70E. The figures from the Advice Note, which are reproduced here in Appendix 2, indicate that the maximum safe value for the interwedge friction angle is ½N.
Critical mechanism
The critical mechanism at any one point in the slope is the mechanism that requires the greatest reinforcement force to establish its equilibrium. The critical mechanism is found by varying the angle of the upper wedge (2
1 mechanism’s heel (X, Y) in the same place.
) while keeping the
T
max
mechanism
The T
max
mechanism is the critical mechanism anywhere in the slope (including the baseline) that requires the greatest reinforcement force to establish its equilibrium.
The T max
mechanism is used to calculate the required number of reinforcement layers
(as described below).
T
ob
mechanism
The T
ob
mechanism is the critical base-sliding mechanism that requires precisely zero reinforcement force to establish its equilibrium. The T ob
mechanism is used to calculate the lengths of the reinforcement layers (as described below).
56 ReActiv 1.7 User Manual
Required reinforcement
The method of calculating the required reinforcement can be summarized as follows:
First, a search is made for the T max
mechanism
Second, the total number of reinforcement layers (n) is calculated from T max
and the long-term design strength of the reinforcement (P des
Third, the depth to the first layer of reinforcement (z
1
Fourth, the pullout length of the first layer (L
A on the following diagram e1
)
) is calculated
) is calculated — this defines point
Fifth, a search is made for the T ob
mechanism — this defines point B on the following diagram
Sixth, the depths of the remaining layers are calculated
Finally, the lengths of all the layers are calculated as the distance from their intersection with line AB to their intersection with the front face of the slope (if the line AB leans to the right, ReActiv sets it to vertical instead, as recommended in the Advice Note)
Number of layers
The total number of reinforcement layers (n) is given by the equation:
n
T
max
P des
1 where P des
(in kN per metre width of slope) is the long-term (factored) design strength of each reinforcement layer. Fractional values of n are not allowed: such values are rounded up to the next whole number.
The "+1" in the equation above ensures that a layer of reinforcement is provided at the base of the slope. As discussed in Appendix G of the Advice Note, this is not a source of over-design.
The terminology used in ReActiv differs from that given in the Advice Note, which uses the symbol N to represent the "minimum number of required layers". N is given by:
N
T
max
P des
Chapter 9: Background theory and assumptions and N + 1 layers of reinforcement are provided.
ReActiv’s symbol n is related to the Advice Note’s N by:
n
N
1
Depth to the first layer
The depth to the first reinforcement layer (z
1
) is given by:
z
1
.
H n
1
57 where H is the height of the (lower) slope and n the total number of reinforcement layers.
Pullout length of the first layer
The pullout length of the first layer of reinforcement (L e1
) is given by:
L e
1
P
n
tan
where 8 p
is the pullout factor; FN n
is the normal effective stress acting on the reinforcement (see below); and N and cN are the soil’s effective stress design parameters. The parameters N and cN in ReActiv correspond to N des
Advice Note.
and cN des
in the
The value of P is taken as the lesser of:
The design strength of the reinforcement (P des
)
T max
Normal effective stress
The normal effective stress (FN n
) that acts on horizontal reinforcement, assuming it is flat, is equal to the vertical effective stress in the soil (FN v length of the reinforcement.
) mid-way along the pullout
Depths of layers 2-n
The depths (z i
) of layers 2 to n are given by:
z i
H i n
1
1
for i
1
The diagram below illustrates a typical arrangement of layers using this formula.
58 ReActiv 1.7 User Manual
Further checks
For most practical design cases, the reinforcement layout defined in the Advice Note will adequately cover all possible intermediate two-part wedge mechanisms. ReActiv may be used to confirm this, by performing spot checks of individual mechanisms, especially for N
12
> 0.
Two-part wedge mechanism with inclined reinforcement
The design method given in the Advice Note for inclined reinforcement is identical to that for horizontal reinforcement, except as described below:
The equation for the total out-of-balance force (T) is more complicated because the components T
1
, T
2
, and T
12
are inclined to the horizontal (see below)
The T max
and T ob
mechanisms are called the T max*
and T o*
mechanisms to emphasize the fact that they are calculated for inclined reinforcement
The average normal effective stress that acts on soil nails is not equal to the vertical effective stress in the soil
Governing equations
The general expression for the out-of-balance inclined reinforcement force (T) required for equilibrium is as given for horizontal reinforcement, except that the equation for zeta (as given below) is different.
.
1
or .
2
?
The assumption that the reinforcement force is carried solely by Wedge 1 (i.e. using
.
) can lead to overly conservative designs for inclined reinforcement, particularly
1 when the angle of interwedge friction (N
12
) is set to zero. This is the combination of parameters that was used to produce Table 4.1 in the Advice Note and is the most conservative set of assumptions that can be made.
The equation for .
1
is:
Chapter 9: Background theory and assumptions
1
cos
1
cos
sin sin
1
tan
tan
12
59
The derivation of this factor is given in the Advice Note.
The alternative assumption, that the reinforcement force is carried solely by Wedge
2 (i.e. using .
2
), leads to less conservative but more reasonable designs. Comparing the results based on .
2
with solutions obtained from Caquot and Kerisel’s charts (see
Appendix 2), indicates that calculations based on .
2 angles (N
12
are safe for interwedge friction
) up to ½N (where N is the angle of shearing resistance of the soil).
The equation for .
2
is:
2
cos
2
s
sin
2 tan
cos
2
sin
s
sin
2
2
s
cos
tan
2
tan
tan
12
T
max*
mechanism
The T max*
mechanism is the mechanism that requires the greatest reinforcement force to establish its equilibrium. This definition is identical to that for the T max the change in notation merely emphasizes the fact that T horizontal, whereas T represent both T max max
and T max*
.
max*
mechanism:
is inclined at –* to the
is horizontal. For simplicity, ReActiv uses the term T max
to
The T max*
mechanism is used to calculate the required number of reinforcement layers (as described below).
T
o*
mechanism
The T
o
*
mechanism is the base-sliding mechanism that requires precisely zero reinforcement force to establish its equilibrium. This definition is identical to that for the T ob
mechanism: the change in notation merely emphasizes the fact that the base of the T o*
mechanism is inclined at –* to the horizontal, whereas the base of the T mechanism is horizontal. For simplicity, ReActiv uses the term T ob
T ob
and T o*
.
ob
to represent both
The T o*
mechanism is used to calculate the lengths of the reinforcement layers (as described below).
Required reinforcement
The method of calculating the required reinforcement is identical to that described previously, except that the normal effective stress (FN ) that is used to calculate the pullout length of the first layer of reinforcement is no longer equal to the vertical effective stress in the soil, owing to the inclination of the reinforcement. FN n calculated as described below.
is
Normal effective stress
The normal effective stress (FN ) that acts on soil nails is given by:
3
4
K a
v
where FN v
is the vertical effective stress in the soil at a point mid-way along the
60 ReActiv 1.7 User Manual pullout length of the nail and K a
is the soil’s coefficient of active earth pressure, given by:
K a
1
1
sin
sin
where N is the soil’s design angle of shearing resistance.
The derivation of the equation for FN n
is given in Appendix D of the Advice Note.
Base-sliding resistance
Base sliding occurs when the lower wedge (Wedge 2) of a two-part wedge mechanism slides directly over the surface of a layer of reinforcement (as shown below).
The base-sliding resistance of the reinforcement is incorporated in the general stability calculations presented previously via the terms RN and K
2
, defined as follows:
R
2
s
N
2
tan
K
2
s
cos
where 8 s
is a non-dimensional sliding factor (defined below); NN and X are defined previously in this chapter; * is the angle of inclination of the reinforcement; and N and cN are the design effective stress parameters of the soil.
The sliding factor (8 s
) depends on the properties of the reinforcement and, in particular, on how much of the sliding surface the reinforcement occupies. The following table summarizes the values of 8 s
that ReActiv adopts for the different types of reinforcement according to whether the angle of the lower wedge (2
2 equals the angle of inclination of the reinforcement (–*) or not.
)
Chapter 9: Background theory and assumptions 61
Wedge angle (2
2
2
2
2
… *
= * ±0.1E
2
) Reinforcement
All
Geotextile
Geogrid
Custom
Soil nails f
8
1
s
ds f ds d h
/S h
+ (1 – d h
/S h
)
In this table, f ds
is the reinforcement’s direct-shear factor; and d h
and S h
are the effective hole diameter and horizontal spacing of the soil nails.
Compatibility with the Advice Note
The Advice Note uses the term interface sliding factor to quantify the reduction in shearing resistance caused by soil sliding over an interface instead of over soil. The interface sliding factor (") is defined as:
tan
tan int
erface soil
c
int
c
erface soil
where N is an angle of friction; cN is an effective cohesion; and the subscripts
interface and soil denote values obtained in soil-on-interface and soil-on-soil tests, respectively. The values are obtained from shearing tests taken to large displacements. The soil parameters in these equations are design values, i.e. they include appropriate partial factors-of-safety or are large-displacement values.
The parameter f ds
Note.
used by ReActiv is identical to the parameter " used in the Advice
Pullout resistance
The pullout resistance (P) of the reinforcement is calculated from the formula:
P
n
tan
where 8 p
is a non-dimensional pullout factor (defined below); L e
is the length of the reinforcement that extends beyond the failure mechanism; FN represents the average normal effective stress acting on the pullout length of the reinforcement; and N and cN are the design effective stress parameters of the soil.
The pullout factor (8 p
) depends on the properties of the reinforcement and, in particular, on its mode of failure in pullout. The following table summarizes the values of 8 p
that ReActiv adopts for the different types of reinforcement.
Reinforcement
Geotextile
Geogrid
Soil nails
Custom
Mode of failure
Direct-shear
Bearing failure on ribs
Direct-shear
Unknown
8
p
2f ds
2f b
Bd h f ds
/S h
2f b
In this table, f ds
and f b
are the reinforcement’s direct-shear and bearing factors,
62 ReActiv 1.7 User Manual respectively; and d h the soil nails.
and S h
are the effective hole diameter and horizontal spacing of
For geotextiles, geogrids, and custom reinforcement, the normal effective stress (FN n is equal to the vertical effective stress (FN v the reinforcement, where:
)
) acting midway along the pullout length of
v
z
q
1
r u
and z is the depth of soil above the reinforcement, midway along its pullout length;
( is the unit weight of the soil; q is the applied surcharge; and r u
is Bishop’s pore pressure parameter for the slope.
For soil nails FN is given by:
n
4
1
3
K a
v
where K a
is given by Coulomb’s equation:
K a
1
1
sin
sin
The value of N in the last equation is the design value.
See Appendix D of the Advice Note for further discussion of the pullout resistance of soil nails.
Compatibility with the Advice Note
The parameter f b
Note.
used by ReActiv is identical to the parameter "N used in the Advice
Minimizing soil nail pullout lengths
Pullout lengths for the top row of soil nails can sometimes be too long to be practical. The Advice Note describes an option whereby the pullout length of the upper layer (L e1
) may be reduced to LN e1
, as shown below, by reducing the horizontal spacing of the upper layer of nails from S h1
to SN h1
, where:
S h
L
e
L e
1
1
S h
1
Chapter 9: Background theory and assumptions 63
As the figure above shows, the zone of required reinforcement is now controlled by the pullout length of the second layer of nails (L e2
) instead of that of the first (L e1
).
Special considerations for Two-part slopes
The equation for layer depths assumes that all geometrically-similar but reduced-scale versions of the T max
mechanism (see below) will automatically be stable if the T max mechanism is made stable. These reduced-scale mechanisms are higher in the slope than the T max
mechanism.
The geometrical similitude required for this assumption breaks down in the case of two-part slopes, where the "mini" T max scale T max
mechanism is more onerous than the reduced-
mechanism (see below), owing to the extra soil shown shaded.
64 ReActiv 1.7 User Manual
In such situations, it is normally sufficient to provide an extra layer of reinforcement at the level of the slope crest.
Surcharges
The Advice Note allows a uniform vertical surcharge on the slope crest to be considered either explicitly or, more simply, as an equivalent additional thickness of fill. ReActiv adopts the latter approach. When a surcharge is specified, the program determines the T max
(HN):
and T ob
mechanisms based on the effective height of the slope
H
H
H
H
q
where H is the actual slope height (in metres); q is the surcharge (in kN/m
2 is the unit weight of fill (kN/m
3
).
); and (
This method is an approximation, and introduces small errors into the calculation of the out-of-balance force. Instead of attributing the extra weight of bcfe to Wedge 1
(see below), ReActiv uses the slightly smaller weight of acfd. ReActiv also
(conservatively) overestimates the pore pressures by r includes cohesion on the surface ac.
u
()H and (unconservatively)
When a surcharge is present, ReActiv calculates layer spacings from the expressions:
z
1
.
H
n
1
Chapter 9: Background theory and assumptions and
z i
i n
1
1
for i
1
65 where n is the total number of layers. The depths (z i the "equivalent" slope, as shown below.
) are measured from the top of
Compatibility with the Advice Note
A number of symbols are used in the ReActiv User Manual that are different from those used in the Advice Note. The following table provides a "translation" between the two documents.
Symbol used in...
ReActiv User Manual
N
T
T f cN f max ob ds n b
Advice Note
N N des cN des
T max
, T max*
T ob
, T o*
"
" N
N + 1
66 ReActiv 1.7 User Manual
Chapter 10
Proceeding to a final design
This chapter of the ReActiv User Manual discusses the results obtained from the program and summarizes the steps that need to be followed in order to proceed to a final design.
The chapter also discusses ReActiv’s limitations and inherent conservatism and compares ReActiv to other calculation methods.
Checking individual mechanisms
The reinforcement layout that ReActiv determines will, for most practical design cases, ensure that all possible two-part wedge mechanisms passing through the reinforced zone are stable. You can check the stability of any particular mechanism by choosing Calculate > Single Mechanism... from the menu bar. This will give you the required reinforcement force: you will have to calculate the available force by hand.
Appendix G of the Advice Note gives guidance on sensible mechanisms to check.
Competent foundation
ReActiv assumes the existence of a competent bearing material directly beneath the slope. If the foundation is not competent, or is not significantly better than the slope material, then underlying slip mechanisms should be checked by alternative means
(for example, Janbu’s or Bishop’s methods, etc.). If the foundation is independently improved (e.g. by replacement or separate stabilization methods), then the reinforcement layout from ReActiv will be relevant. If the foundation is not independently improved (more likely to be the case for cuttings than for embankments), then the reinforced zone may need extending and/or increasing in density, as dictated by the results of slip calculations for mechanisms which penetrate the underlying soils.
Front facing
In most practical cases you will need to provide front face protection to the slope to guard against damage caused by ultra-violet radiation, fire, and/or vandalism.
ReActiv implicitly assumes the presence of a "structural" front facing (e.g. wraparound construction, in the case of geotextiles and geogrids, or shotcrete or similar, in the case of soil nailing).
Appendix G of the Advice Note discusses the effects of the absence of structural facings
Checking pullout of the base layer
ReActiv implicitly assumes that the T ob
mechanism allows sufficient pullout length on the base layer of reinforcement behind the T max
mechanism. In extreme cases, where the reinforcement has a long pullout length requirement (perhaps widely spaced, high strength strip reinforcement or soil nails), this may not be the case and should be checked, and the base width of the reinforcement zone extended as necessary.
This is not normally necessary.
Elongation of reinforcement
Elongation of the reinforcement under working conditions needs to be checked in terms of both the serviceability requirements of the reinforced slope, and also strain
Chapter 10: Proceeding to a final design 67 compatibility with the soil. (A method for estimating front face displacements for the former can be found at the end of Section 3 of the Advice Note.) Strain compatibility with the soil is important if N = N critical state
is not selected. The reinforcement should not be so extensible that the soil strength passes through "peak" and starts "strain softening" to below its design strength before the reinforcement has picked up its working load.
Drainage
Drainage measures should be provided as appropriate to ensure that the pore pressures assumed in the analysis will never be exceeded. The design should also be checked for the potential effects of water filled tension cracks, if it is likely that these would form behind the reinforced zone.
Inherent conservatism of a frictionless interwedge boundary
ReActiv’s calculation method is based on the two-part wedge mechanism with a vertical interwedge boundary. The User may specify whether the interwedge boundary is frictional or frictionless, and may also specify what wedge the reinforcement force should be applied to. The mechanism is simple enough to check by hand-calculation, is intuitive, and is particularly suited to the case of base sliding over a planar layer of reinforcement.
The assumption of a frictionless interwedge boundary (i.e. N
12
= 0) yields inherently conservative values of out-of-balance reinforcement force when compared to more exact solutions (e.g. Caquot & Kerisel, Sokolovsky, and the log spiral method), by typically 10 to 30% in terms of reinforcement density and 5 to 10% in terms of reinforcement length. In cases where these percentages do not represent a significant extra cost to the project as a whole, then setting N
12
= 0 is attractive in that it is inherently conservative and relieves the designer of having to justify the actual distribution of the reinforcement force (see Chapter 8).
In cases where these percentages do represent a significant extra cost to the project as a whole, ReActiv allows the User to take into account friction on the interwedge boundary (although it is recommended that N
12
is never taken to be greater than
½N). As explained in Chapter 8, this requires some assumption to be made about the distribution of the reinforcement force between the two wedges.
ReActiv allows you to choose between having all the reinforcement force acting on
Wedge 1 or all on Wedge 2. The latter option is preferable since it yields a lower reinforcement requirement and a better conditioned set of equations. It is considered to be a reasonable assumption for most design cases and, for this reason, is the program default.
If interwedge friction is employed, then you should satisfy yourself that it is reasonable to place all the reinforcement force on Wedge 2 (if that is the option you choose). See Chapter 8 for information on doing this. You should also look at the shape of the T max
mechanism relative to the reinforcement layout and check that most of the reinforcement force does indeed act on Wedge 2 (note, in this context, that it is the top of the interwedge boundary that determines where the force from a particular layer of reinforcement acts). For borderline cases (typically for slopes with small angles), you are advised to check how different the design layout is if you adopt the alternative assumption of all the reinforcement force on Wedge 1 or change the interwedge friction angle.
Using ReActiv to check other design methods
When checking a design which does not adopt the optimum layer spacing theory
68 ReActiv 1.7 User Manual embodied in the Advice Note (e.g. designs which adopt constant vertical spacing with depth or multiples of fixed vertical spacings) then ReActiv may not be used in
"automatic" mode. ReActiv can however be usefully employed to identify the key mechanisms (T max
, T ob
) against which the design can be assessed. The Advice Note suggests that any design is acceptable provided that:
The T max
and T ob
mechanisms are satisfied
All intermediate mechanisms are sufficiently catered for
No individual layers are locally over-stressed
The available force from the lengths of reinforcement projecting beyond the mechanism in question may then be compared, by hand calculation or otherwise, with the required force (calculated by ReActiv).
Chapter 11: Comparison with published results 69
Chapter 11
Comparison with published results
This appendix compares results obtained by GCG ReActiv with those published in the geotechnical literature by Sokolovski, Caquot and Kerisel, and Jewell. In each case, the maximum out-of-balance force (T max
) has been compared at varying slope angles ($). To facilitate these comparisons, T max
has been normalized as follows:
K
1
2
T
max
H
2 were ( is the unit weight of the soil and H is the height of the slope. Other parameters that have been varied are N, cN, N
12
, *, 8 s
, i, and r u
; and whether the reinforcement force acts on Wedge 1 or 2. See Chapter 9 for a full explanation of these terms and symbols.
Horizontal reinforcement
The following figures present values of K obtained by ReActiv for horizontal reinforcement with varying angles of interwedge friction (N
12
= 0, N
12
= N/2, and N
12
= N). Also shown are results presented by Sokolovski, Caquot and Kerisel, and Jewell.
In most cases, setting N
12
= N/2 yields results that are in reasonable agreement with the published values. In all cases, setting N
12
= 0 yields conservative values of K (i.e.
values above the published results) and setting N
12
(i.e. values below the published results).
= N yields unconservative values
Parameters for the following figure are: * = 0, 8 s
= 1, i = 0, r u
= 0, N = 20E, cN = 0.
Parameters for the next figure are as above, except N = 40E.
70 ReActiv 1.7 User Manual
Parameters for the next figure are: * = 0, 8 s
= 1, i = 0, r u
= 0.5, N = 30E, cN = 0.
Parameters for the next figure are as above, except r u
= 0.25.
Inclined reinforcement
The following figures present values of K obtained by ReActiv for inclined
Chapter 11: Comparison with published results 71 reinforcement with varying angles of interwedge friction (N
12
= 0 and N
12
= N/2) and varying the wedge on which the tension force acts (Wedge 1 or 2). Also shown are results derived from Caquot and Kerisel.
In all cases, applying the tension force on Wedge 1 yields conservative values of K
(i.e. values above the published results).
Less conservative values of K are obtained when the tension force is applied to
Wedge 2 and N
12
is set to zero. However, the best fit to the published results is obtained when the tension force is applied to Wedge 2 and N
12
is set to N/2.
Unfortunately, with this combination of parameters, the results are unconservative at low slope angles.
By default, ReActiv applies the tension force to Wedge 2 and sets N
12
This is conservative.
equal to zero.
Parameters for the following figure are: * = 10E, 8 s
= 1, i = 0, r u
= 0, N = 40E, cN = 0.
Parameters for the next figure are as above, except N = 20E.
Parameters for the next figure are: * = 20E, 8 s
= 1, i = 0, r u
= 0, N = 40E, cN = 0.
Parameters for the next figure are as above, except N = 20E.
72 ReActiv 1.7 User Manual
Chapter 12: Further examples 73
Chapter 12
Further examples
The examples described in this chapter are identical to the examples given in
Appendix J of the UK Highways Agency’s Advice Note. If you have a copy of the
Advice Note, you may find it helpful to read the relevant pages before working through this chapter.
Exploring ReActiv’s capabilities
If you have worked through the worked examples given in Chapters 4-6, you will already know how easy ReActiv is to use and how quickly it performs the calculations necessary to design a reinforced slope. Moreover, there is still plenty of scope for you to experiment with the program. In particular, you can:
Change the water regime in the slope
Change the surcharge that acts at the crest of the slope
Change the type and properties of the reinforcement
Calculate the reinforcement required to stabilize the slope
Change various options that control those calculations
Change the project information attached to the document
Print the input and output data for the supplied examples
Preview the printer’s output on screen
In order to obtain a better appreciation of ReActiv’s technical capabilities, we recommend that you try changing some or all of the options listed above and see what effect this has on the results of the calculations.
If you want to check that ReActiv is producing correct results, you can run one or more of the supplied examples anc compare the results with those given in the
Advice Note.
Supplied examples
A number of example projects are copied onto your hard disk when you install
ReActiv. The projects have been given the names EXAMPLEn.RAV, where n is an integer between 1 and 7. The examples have been taken from Appendix J of the
Advice Note and are described briefly on the following pages (please note that
Example 4 is intentionally missing).
Example 1: embankment in dense sand
Example 1 is described in Tutorial 1 on page 24.
Example 2: embankment in stiff clay
Example 2 comprises a 10m high slope made out of stiff clay, which is reinforced by horizontal geotextiles so that it can stand at 30E to the horizontal.
The clay has an angle of shearing resistance of 20E, effective cohesion of 1kN/m², and a bulk density of 19kN/m³. Bishop’s pore pressure parameter for the slope (r u is 0.25. There is a surcharge of 10kN/m
2
at the top of the slope.
)
The reinforcement has a design strength of 28.9kN/m (after applying various factorsof-safety to it). The geotextile’s direct shear factor is 0.95 (in the Advice Note, this parameter is called the interface sliding factor, "). Since the Advice Note does not allow for interwedge friction, the interwedge friction factor is set to zero.
74 ReActiv 1.7 User Manual
You will find a copy of this project in Windows’ Shared Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\EXAMPLES\EXAMPLE2.RAV
T
max
mechanism
According to ReActiv, the mechanism with the largest out-of-balance force anywhere in the slope (i.e. the T max
mechanism) has the following properties:
X = 13.27m, Y = 0.00m, 2
1
= 46.4E, T max
= 301.68kN/m
In the Advice Note, the equivalent height of the slope (HN) is rounded down to
10.5m from 10.53m. This causes the Advice Note to give slightly different results to those obtained by ReActiv (i.e. T max
= 298kN/m).
T
ob
mechanism
The critical mechanism that requires exactly zero reinforcement to be stable (i.e. the
T ob
mechanism) has the following properties:
X = 22.46m, Y = 0.00m, 2
1
= 55.0E, T max
= 0.00kN/m
The X-value is in close agreement with the length L
B
(despite the rounding mentioned above).
given in the Advice Note
Required reinforcement
The slope being analysed requires twelve layers of reinforcement and, for the most efficient layout, the layers would be placed at the following depths:
1.06, 2.65, 3.96, 4.97, 5.82, 6.57, 7.25, 7.87, 8.45, 9.00, 9.51, and 10.00m
These depths are identical to those given in the Advice Note. The required length of the layers varies from 8.14m at the top to 22.46m at the bottom.
Example 3: cutting in stiff clay
Example 3 is described in Tutorial 2 on page 30.
Example 5: slip repair in stiff clay
Example 5 comprises a 7m high embankment made out of stiff clay. The embankment has suffered a surface slip which is to be repaired by replacing the slipped material with soil reinforced by geotextiles. The slope is to stand at an angle of 26.56E to the horizontal (i.e. 1:2 vertical to horizontal).
From a back analysis of the slip, the clay has an angle of shearing resistance of 20E, effective cohesion of 1.5kN/m², and a bulk density of 20kN/m³, assuming Bishop’s pore pressure parameter for the slope (r u
) is 0.0. For design purposes, however, the angle of shearing resistance is to be reduced to 18.3E and the effective cohesion to
0kN/m². There is no surcharge at the top of the slope.
The reinforcement has a design strength of 15.8kN/m (after applying various factorsof-safety to it). The geotextile’s direct shear factor is 0.8 (in the Advice Note, this parameter is called the interface sliding factor, "). Since the Advice Note does not allow for interwedge friction, the interwedge friction factor is set to zero.
You will find a copy of this project in Windows’ Shared Documents folder, located at:
Chapter 12: Further examples
GEOCENTRIX\REACTIV\1.7\EXAMPLES\EXAMPLE5.RAV
75
T
max
mechanism
According to ReActiv, the T max
mechanism has the following properties:
X = 8.79m, Y = 0.00m, 2
1
= 42.3E, T max
= 76.96kN/m
These values are in close agreement with the Advice Note.
T
ob
mechanism
The T ob
mechanism has the following properties:
X = 13.90m, Y = 0.00m, 2
1
= 54.1E, T max
= 0.00kN/m
The X-value is in close agreement with the length L
B
given in the Advice Note.
Required reinforcement
The slope being analysed requires six layers of reinforcement and, for the most efficient layout, the layers would be placed at the following depths:
1.57, 3.13, 4.43, 5.42, 6.26, and 7.00m
These depths are identical to those given in the Advice Note. The required length of the layers varies from 4.83m at the top to 13.90m at the bottom.
Example 6: cutting with unstable upper slope
Example 6 comprises a 9m high two-part slope, made out of stiff clay. The lower part of the slope is 3m high and is to stand at 60E to the horizontal. The upper part of the slope is 6m high and is to stand at 27E to the horizontal. The slope is reinforced by inclined soil nails.
The clay has an angle of shearing resistance of 22E, effective cohesion of 2kN/m², and a bulk density of 20kN/m³. Bishop’s pore pressure parameter for the slope (r u is 0.25. There is no surcharge at the top of the slope.
)
The reinforcement has a design strength of 41.8kN/m (after applying various factorsof-safety to it). The 16mm diameter soil nails are inclined at 10E to the horizontal, and are spaced at 1m intervals horizontally in the lower slope and at 2m intervals horizontally in the upper slope. The holes in which they are installed are 150mm in diameter. The nails’ direct shear factor is 0.8 (in the Advice Note, this parameter is called the interface sliding factor, "). Since the Advice Note does not allow for interwedge friction, the interwedge friction factor is set to zero.
Analysing two-part slopes
When ReActiv analyses a Two-part slope, it determines the reinforcement required to stabilize the lower part, assuming that the upper slope is stable (and therefore requires no reinforcement). If the upper slope is not stable, it is necessary to conduct a second analysis in order to determine what reinforcement should be placed in the upper slope to correct this.
To analyse the upper slope, all you need to do is the regard the lower slope as a competent bearing foundation and to treat the upper slope as if it were a One-part slope. In the example considered here, that means treating the upper slope as a 6m high slope standing at 27E to the horizontal.
76 ReActiv 1.7 User Manual
The example project that are supplied with ReActiv illustrate how this can be done.
The file EXAMPLE6.RAV can be used to determine the reinforcement required to stabilize the lower slope and EXAMPLE7.RAV to determine the reinforcement required to stabilize the upper slope.
You will find a copy of Example 6 in Windows’ Shared Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\EXAMPLES\EXAMPLE6.RAV
T
max
mechanism
According to ReActiv, the T max properties:
mechanism for the lower slope has the following
X = 9.54m, Y = 2.00m, 2
1
= 46.4E, T max
= 140.13kN/m
These values differ from the Advice Note because, by default, ReActiv applies all the reinforcement force to Wedge 2 (the lower wedge), whereas in the Advice Note the reinforcement force is applied to Wedge 1 (the upper wedge). A full discussion of these issues can be found in Chapter 9.
To reproduce the results given in the Advice Note, choose Options | Tension on
Wedge 1 from the menu bar and answer Yes to the question asking whether you want to proceed. When you recalculate T max
, it has the following properties:
X = 8.92m, Y = 1.44m, 2
1
= 47.1E, T max
= 159.4kN/m
These values are in reasonable agreement with the Advice Note (which gives X =
8.0m, Y = 0.8m, 2
1
= 45E, and T max
= 160kN/m).
T
ob
mechanism
With the Tension on Wedge 1 option set, the T ob properties:
mechanism has the following
X = 10.93m, Y = –1.93m, 2
1
= 53.8E, T max
= 0.00kN/m
The X-value is in reasonable agreement with the length L
B
(which gives L
B
= 10.7m).
given in the Advice Note
Required reinforcement
The slope being analysed requires five layers of reinforcement and, for the most efficient layout, the layers would be placed at the following depths:
0.75, 1.50, 2.12, 2.60, and 3.00m
The required length of the layers varies from 10.39m at the top to 11.0m at the bottom.
Example 7: upper slope of Example 6
Example 7 comprises the upper slope of Example 6 (see above).
You will find a copy of Example 7 in Windows’ Shared Documents folder, located at:
GEOCENTRIX\REACTIV\1.7\EXAMPLES\EXAMPLE7.RAV
Chapter 12: Further examples 77
T
max
mechanism
According to ReActiv, the T max properties:
mechanism for the upper slope has the following
X = 7.24m, Y = 0.10m, 2
1
= 41.5E, T max
= 32.17kN/m
These values differ from the Advice Note because, by default, ReActiv applies all the reinforcement force to Wedge 2 (the lower wedge), whereas in the Advice Note the reinforcement force is applied to Wedge 1 (the upper wedge). A full discussion of these issues can be found in Chapter 9.
To reproduce the results given in the Advice Note, choose Options | Tension on
Wedge 1 from the menu bar and answer Yes to the question asking whether you want to proceed. When you recalculate T max
, it has the following properties:
X = 5.31m, Y = –0.94m, 2
1
= 37.9E, T max
= 36.41kN/m
These values differ slightly from the results given in the Advice Note, but the difference is not of engineering significance.
T
ob
mechanism
With the Tension on Wedge 1 option set, the T ob properties:
mechanism has the following
X = 8.52m, Y = –1.50m, 2
1
= 49.6E, T max
= 0.00kN/m
The X-value is in reasonable agreement with the length L
B
(which gives L
B
= 8.4m).
given in the Advice Note
Required reinforcement
The slope being analysed requires three layers of reinforcement and, for the most efficient layout, the layers would be placed at the following depths:
2.12, 4.24, and 6.00m
The required length of the layers varies from 9.14m at the top to 8.65m at the bottom.
78 ReActiv 1.7 User Manual
Chapter 13
Soil Classification System
The Soil Classification System used by ReActiv is based on a combination of:
The British Soil Classification System (BSCS), as described in BS 5930:1981
The Unified Soil Classification System (USCS), as described in ASTM D2487-1069
The German Soil Classification System (DIN), as decribed in DIN 18 196
In addition to the basic groupings of Gravel, Sand, Silt, and Clay that are common to all these systems, the Soil Classification system includes commonly-encountered soils under the headings Organic, Fill, Chalk, Rock, River Soil, and Custom.
The following table lists the soils that are included in the Soil Classification System and give the corresponding group symbols from each of the established systems listed above (where they are available).
Class
Unclassified*
Well-graded
Uniformly-gr’d
Gap-graded
Silty
Clayey*
Very silty*
Very clayey*
Unclassified*
Well-graded
Uniformly-gr’d
Gap-graded
Silty
Clayey*
Very silty*
Very clayey*
Unclassified
Gravelly
Sandy
Low-plasticity
Unclassified*†
Int.-plast.*†
High-plast.*†
S
SW
SPu
SPg
S-M
S-C
SM
SC
M
MG
MS
ML
Symbol
G
GW
GPu
GPg
G-M
G-C
GM
GC
M
MI
MH
S
SW
SPu
SPg
S-M
S-C
SM
SC
M
MG
MS
ML
BSCS
G
GW
GPu
GPg
G-M
G-C
GM
GC
M
MI
MH-ME
S
SW
SP
SP
S?-SM
S?-SC
SM
SC
M
ML/MH
ML/MH
ML
USCS
G
GW
GP
GP
G?-GM
G?-GC
GM
GC
M
ML
MH
U
-
-
UL
S
SW
SE
SI
SU
ST
SU
ST
DIN
G
GW
GE
GI
GU
GT
GU
GT
States
Unpecified (Unsp)
Very loose (VL)¶
Loose (L)
Medium dense (MD)
Dense (D)
Very dense (VD)
Poorly comp’d (PC)
Well comp’d (WC)
Same as GRAVEL
Unpecified (Unsp)
Very loose (VL)¶
Loose (L)
Medium dense (MD)
Dense (D)
Very dense (VD)
Same as CLAY
U
UM
-
Unclassified*†$
Gravelly*†
Sandy*†
Low-plast.*†
Int.-plast.*†$
High-plast.*†$
Laminated*†
Unclassified†
Organic clay†
Organic silt†
Peat†
Loam†
C
CG
CS
CL
CI
CH
Lam
O
MO
CO
Pt
Loam
C
CG
CS
CL
CI
CH-CE
-
O
MLO/H
CLO/H
Pt
-
C
CL/CH
CL/CH
CL
CL
CH
-
O
OL
OH
Pt
-
TL
TM
TA
-
T
-
-
O
(OU)
OT
HN/HZ
-
Unspecified (Unsp)*$
Very soft (VSo)
Soft (So)
Firm (F)*$
Stiff (St)*$
Very stiff (VSt)*$
Hard (H)*$
Same as CLAY
Chapter 13: Soil Classification System 79
Class
Unclassified
Rock fill
Slag fill
Gravel fill
Sand fill
Chalk fill
Brick hardcore
Ashes
PFA
Clay fill†
Unclassified*
Grade I*
Grade II*
Grade III*
Grade IV*
Grade V
Grade VI
Marl*
Weathered rock*
River mud†
Dock silt†
Alluvium†
Symbol
MdG
RockF
Slag
GravF
SandF
ChkF
Brick
Ash
PFA
ClayF
Chk
Chk1
Chk2
Chk3
Chk4
Chk5
Chk6
Marl
Rock
RivM
DockS
Alluv
BSCS USCS
Custom*†$ Cust
G? = G, GW, or GP; S? = S, SW, or SP; Int. = intermediate; plast. = plasticity
*may have effective cohesion (if symbol appears next to Class & State)
†may be undrained
$may be fissured (if symbol appears next to Class & State)
¶potential for liquefaction
DIN States
Unspecified
Poorly-comp’d (PC)
Well-compacted (WC)
Same as CLAY
Unspecified (Unsp)
Unspecified (Unsp)
Unspecified (Unsp)
Very soft (VSo)
Soft (So)
Unspecified (Unsp)*$
Database of soil properties
ReActiv uses a database of soil properties to check that any parameters you enter for a soil are compatible with that soil’s engineering description.
ReActiv’s checking system is based on the concept that there are normal and
extreme ranges for each soil parameter.
If you enter a value that is outside the extreme range for a particular soil parameter,
ReActiv issues an error message and prevents you from proceeding until you have changed the offending value.
If you enter a value that is outside the normal range, ReActiv issues a warning message and allows you to proceed only if you confirm that the value entered is correct.
The default parameters are provided to assist in initial design studies only, and should not be used as a substitute for measured parameters. As in all forms of geotechnical design, parameters should be chosen on the basis of adequate site investigation, including suitable laboratory and field measurements.
The publications that have been referred to in compiling the database include:
Terzaghi & Peck (1967)
NAVFAC DM-7 (1971)
Peck, Hanson, & Thornburn (1974)
Winterkorn & Fang (1975)
80
ρ d
(kg/m 3 )
ρ s
(kg/m 3 )
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
ReActiv 1.7 User Manual
Canadian Foundation Engineering Manual (1978)
Reynolds & Steedman (1981)
Bell (1983)
Mitchell (1983)
TradeARBED’s Spundwand-Handbuch Teil 1, Grundlagen (1986)
Bolton (1986)
Clayton & Militiski (1986)
Clayton (1989)
Tomlinson (1995)
British Steel’s Piling Handbook (1997)
Invaluable advice regarding the properties of various soils was provided by
Professors JB Burland, PR Vaughan, and DW Hight and by Dr G Sills.
In the following table D friction; N crit d
= dry density; D
= critical state angle of friction; c’ critical state effective cohesion; S w
= wet density; N peak
= peak angle of peak
= peak effective cohesion; c’ u
= undrained shear strength; )S u crit
=
= rate of increase in S u
with depth.
Parameter
φ peak
(deg)
All
G
G_C
GM
GC
Others
G
G_C
GM
GC
Others
Classification
Class
All
All
All Unsp
VL
L
MD
D
VD
PC
WC
Unsp
VL
L
MD
D
VD
PC
WC
State
Unsp
VL
L
MD
D
VD
PC
WC
All
All
All
All
All
Minimum
28
28
30
35
40
45
28
35
1500
1500
1700
1800
1900
2000
1500
1800
Ext.
1200
1200
1300
1400
1500
1700
1200
1400
28
0
35
32
35
40
45
50
35
45
1800
1700
1800
1900
2000
2200
1800
2000
Normal
1400
1300
1400
1500
1700
2000
1400
1700
35
0
0 0
Default
37
34
37
42
47
52
37
47
37
0
2200
1850
2000
2100
2200
2250
2000
2200
2050
1500
1650
1850
2050
2250
1650
2050
Not applicable
0 0
Not applicable
Maximum
50
38
40
45
50
55
40
50
2300
1900
2100
2200
2300
2400
2100
2300
Normal
2200
1600
1800
2000
2200
2400
1800
2200
40
0
60
40
45
50
55
60
50
60
2500
2100
2200
2300
2400
2500
2300
2500
Ext.
2500
1800
2000
2200
2400
2500
2200
2500
45
10
5
Chapter 13: Soil Classification System
Parameter
ρ d
(kg/m 3 )
ρ s
(kg/m 3 )
φ peak
(deg)
†Reduced to allow for potential liquefaction
φ crit
(deg) c’ peak
(kPa) discounting natural cementation c’ crit
(kPa)
ρ d
(kg/m
3
)
ρ s
(kg/m
3
)
φ peak
(deg)
†Reduced to allow for potential liquefaction
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
ρ d
(kg/m
3
)
ρ s
(kg/m
3
)
φ peak
(deg)
All
All
All
All
All
M
MI
MH
S
S_C
SM
SC
Others
All
All
All
Classification
Class
All
All
All
All
S
S_C
SM
SC
Others
State
Unsp
VL
L
MD
D
VD
PC
WC
Unsp
VL
L
MD
D
VD
PC
WC
Unsp
VL
L
MD
D
VD
PC
WC
All
All
All
All
All
All
All
Unsp
VL
L
MD
D
VD
All
All
All
All
All
All
0
0
0
1100
1500
1100
1500
20
20†
23
25
27
30
20
17
17
17
Minimum
33
37
23
29
20
20†
26
29
1600
1600
1750
1800
1850
1950
1600
1800
Ext.
1200
1200
1225
1275
1350
1450
1200
1275
23
0
30
25†
30
33
36
40
30
36
1800
1750
1800
1850
1950
2050
1800
1950
Normal
1275
1225
1275
1350
1450
1575
1275
1450
30
0
37
42
32
37
32
26†
32
34
32
0
2075
1900
1950
1975
2075
2175
1950
2075
1675
1450
1500
1575
1675
1800
1500
1675
Default Maximum
40
28†
35
37
40
45
35
40
2150
1975
2000
2050
2150
2250
2000
2150
Normal
1800
1550
1600
1700
1800
1900
1600
1800
35
0
55
30†
40
45
50
55
45
55
2400
2000
2050
2150
2250
2400
2150
2400
Ext.
2200
1750
1850
1950
2050
2200
1950
2200
40
10
81
0
Not applicable
0 0
0
0
1275
1800
1275
1800
27
25†
27
28
29
32
27
25
25
20
Not applicable
1850
2050
28
26†
28
29
30
33
28
0
0
1850
2050
28
28
23
5
0
2150
2150
2150
2150
33
28†
31
32
33
36
31
35
35
30
5
10
5
2200
2400
2200
2400
45
30†
35
37
40
45
35
45
40
35
82
Parameter
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
S u
(kPa)
∆S u
(kPa)
ρ d
(kg/m
3
)
ρ s
(kg/m 3 )
φ peak
(deg)
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
C
CG
CS
CL
Cl
CH
Lam
All
C
CG
CS
CL
Cl
CH
Lam
Classification
Class
M
MI
MH
All
State
All
All
All
All
All
All
VSo-So
Others
Unsp
VSo
So
F
St
VSt
H
Unsp
VSo
So
F
St
VSt
H
All
VSo-So
Others
VSo-So
Others
Unsp
VSo
So
F
St
VSt
H
All
All
Unsp
VSo
So
Others
VSo-So
Others
ReActiv 1.7 User Manual
Minimum
-100
-100
1200
1200
1300
1450
1600
1750
1900
1200
1200
1300
1450
1600
1750
1900
15
18
18
20
18
15
15
0
0
0
0
0
0
8
18
18
18
18
8
8
Ext.
17
20
17
0
0
0
0
1
1
10
30
60
100
200
-10
-10
1500
1400
1500
1650
1800
1950
2100
1500
1400
1500
1650
1800
1950
2100
20
20
20
24
20
16
16
0
0
0
0
0
0
20
20
20
20
20
15
12
Normal
22
22
18
0
0
0
0
20
5
20
40
75
150
300
Default
0
0
2050
1650
1750
1900
2050
2200
2300
2050
1650
1750
1900
2050
2200
2300
20
24
24
27
23
20
19
0
0
0
0
0
2
23
24
24
23
23
18
16
0
0
20
10
25
50
100
200
375
0
0
25
25
19
Maximum
4
8
2200
1800
1900
2050
2200
2350
2400
2200
1800
1900
2050
2200
2350
2400
33
33
33
28
28
20
20
33
33
33
33
30
27
25
0
0
10
0
0
10
Normal
30
30
22
0
0
0
5
150
20
40
75
150
300
500
100
100
2500
2000
2100
2250
2400
2450
2500
2500
2000
2100
2250
2400
2450
2500
39
39
39
30
30
22
22
39
39
39
39
37
31
39
0
5
15
0
0
15
Ext.
32
32
25
0
5
0
10
1000
30
60
100
200
400
1000
Chapter 13: Soil Classification System
Parameter
S u
(kPa)
∆S u
(kPa)
ρ d
(kg/m
3
)
ρ s
(kg/m
3
)
φ peak
(deg)
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
S u
(kPa)
∆S u
(kPa)
ρ d
(kg/m
3
) MdG
RockF
Slag
GravF
SandF
ChkF
Brick
Ash
PFA
Uncl
MO
CO
Pt
Loam
Uncl
MO
CO
Pt
Loam
Uncl
MO
CO
Pt
Loam
Uncl
MO
CO
Pt
Loam
All
All
All
Classification
Class
All
All
State
Unsp
VSo
So
F
St
VSt
H
VSo-So
Others
All
All
All
All
All
All
All
Unsp
VSo
So
F
St
VSt
H
VSo-So
Others
All
1
1
10
30
60
100
200
-100
-100
600
1400
1000
1200
1200
1250
1100
600
900
Minimum
-100
-100
800
1000
1000
800
1450
850
1400
1400
850
1450
Ext.
1
1
10
30
60
100
200
18
18
18
18
20
18
18
18
18
20
Default Maximum
20
5
20
40
75
150
300
-10
-10
1225
1500
1200
1400
1225
1300
1300
650
1000
-10
-10
1000
1250
1250
1000
1650
1050
1500
1500
950
1650
Normal
20
5
20
40
75
150
300
20
20
20
20
24
20
20
20
20
24
23
23
23
23
27
23
23
23
23
27
1500
1500
1500
1200
1900
1650
1650
1650
1250
1900
20
10
25
50
100
200
375
0
0
Not applicable
Not applicable
20
10
25
50
100
200
375
0
0
1600
1900
1450
1950
1600
1350
1600
1000
1350
8
8
2050
1600
1600
1300
2050
2050
1750
1750
1400
2050
Normal
150
20
40
75
150
300
500
30
30
30
30
33
30
30
30
30
33
150
20
40
75
150
300
500
8
8
1800
2100
1600
2200
1800
1400
1750
1000
1500
1000
30
60
100
200
400
1000
100
100
2500
2200
1800
2500
2200
1450
1900
1200
1700
100
100
2250
1750
1750
1400
2250
2250
1950
1950
1500
2250
Ext.
1000
30
60
100
200
400
1000
39
37
37
37
39
39
37
37
37
39
83
84
Parameter
ρ s
(kg/m 3 )
φ peak
(deg)
φ crit
(deg)
ρ d
(kg/m 3 )
ρ s
(kg/m 3 )
φ peak
(deg)
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
S u
(kPa)
∆S u
(kPa)
ρ d
(kg/m
3
)
Classification
Class State
All
All
All
All
All
MdG
RockF
Slag
GravF
SandF
ChkF
Brick
Ash
PFA
MdG
RockF
Slag
GravF
SandF
ChkF
Brick
Ash
PFA
MdG
RockF
Slag
GravF
SandF
ChkF
Brick
Ash
PFA
All
All
All
All
All
All
All
All
Unsp
VSo
So
F
St
VSt
H
All
All
All
All
VSo-So
Others
Chk
Chk1
Chk2
Chk3
Chk4
Chk5
Chk6
ReActiv 1.7 User Manual
1
1
10
30
60
100
200
-100
-100
1255
1525
1350
1275
1250
1225
1225
Minimum
25
30
25
28
23
25
25
27
27
950
23
35
25
28
23
25
35
30
27
1300
15
15
Ext.
1200
1750
1400
1500
1600
1700
1400
1200
1350
Default Maximum
20
5
20
40
75
150
300
-10
-10
1275
1650
1400
1325
1300
1275
1275
30
35
30
35
30
30
30
30
30
1100
30
40
30
35
30
30
40
35
30
1500
17
17
Normal
1650
1900
1700
1800
1800
1750
1650
1300
1500
2000
2100
1850
2150
2050
1825
1850
1450
1750
32
37
32
37
32
32
32
33
32
1550
35
43
33
40
32
32
42
37
32
1850
21
21
Not applicable
Not applicable
20
10
25
50
100
200
375
0
0
1450
2050
1575
1450
1375
1350
1350
Normal
2150
2200
1900
2300
2150
1850
1950
1500
1800
150
20
40
75
150
300
500
8
8
2250
2250
1650
1500
1425
1400
1400
35
40
35
40
35
35
35
38
35
1750
45
50
40
50
35
37
45
40
37
2050
30
28
1000
30
60
100
200
400
1000
100
100
2500
2500
1725
1550
1475
1450
1450
45
45
45
45
40
40
40
42
40
1900
60
60
50
60
40
43
50
45
40
2250
35
30
Ext.
2500
2300
2000
2500
2400
1900
2100
1800
2000
Chapter 13: Soil Classification System
Parameter
ρ s
(kg/m 3 )
φ peak
(deg)
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
ρ d
(kg/m
3
)
ρ s
(kg/m
3
)
φ peak
(deg)
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
ρ d
(kg/m
3
)
ρ s
(kg/m
3
)
φ peak
(deg)
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
S u
(kPa)
∆S u
(kPa)
ρ d
(kg/m
3
)
ρ s
(kg/m
3
)
φ peak
(deg)
All
All
All
All
All
All
Classification
State
All
All
All
All
Chk
Chk1
Chk2
Chk3
Chk4
Chk5
Chk6
All
All
All
All
Chk
Chk1
Chk2
Chk3
Chk4
Chk5
Chk6
All
Class
Chk
Chk1
Chk2
Chk3
Chk4
Chk5
Chk6
All
Uncl
Uncl
Uncl
All
All
All
All
Unsp
VSo
So
Unsp
VSo
So
Unsp
VSo
So
All
Unsp
Unsp
Unsp
1
1
10
-100
600
850
10
Minimum
2050
27
27
0
0
0
0
0
0
0
0
0
2050
25
25
25
25
25
25
25
25
Ext.
1725
1925
1800
1750
1750
1725
1725
0
1200
1200
1200
1200
1200
1200
15
15
Default Maximum
20
5
20
-10
1200
1200
20
0
1600
1600
1650
1600
1600
1650
22
22
2250
33
33
5
0
0
5
2
0
10
5
0
2250
35
35
34
34
33
32
32
1900
2300
1975
1900
1850
1825
1825
32
Not applicable
Not applicable
20
10
25
0
2000
2000
30
2300
38
38
10
20
20
20
20
10
0
0
0
2300
45
45
43
41
39
37
35
35
Normal
2450
2450
2025
1925
1875
1850
1850
0
1800
1800
1800
1800
1800
1800
33
33
40
20
40
4
2400
2400
50
2100
30
30
0
0
0
0
0
0
0
0
0
2100
30
30
30
30
30
30
30
30
Normal
1750
2025
1850
1800
1775
1750
1750
0
1250
1250
1400
1250
1250
1400
16
16
60
30
60
100
2500
2600
60
2500
42
42
20
100
100
50
50
20
0
0
5
2500
55
55
52
49
46
43
40
40
Ext.
2600
2600
2075
1950
1900
1900
1900
5
2000
2000
2000
2000
2000
2000
39
39
85
86
Parameter
φ crit
(deg) c’ peak
(kPa) c’ crit
(kPa)
S u
(kPa)
)S u
(kPa)
Classification
Class
Uncl
Uncl
Uncl
Uncl
Uncl
State
Unsp
Unsp
Unsp
Unsp
Unsp
ReActiv 1.7 User Manual
Minimum
Ext.
8
0
0
Normal
20
0
0
1
-100
5
-10
Default
25
0
0
20
0
Maximum
Normal
35
10
0
Ext.
45
100
5
300
10
1000
100
advertisement
Key Features
- Reinforced slope analysis
- Soil nailing design
- Two-part wedge mechanism
- Tmax and Tob mechanism calculations
- Reinforcement layout and spacing
- Design method according to HA68
- Soil classification system and database
- Various soil types and water regimes