Geocentrix 1.7 ReActiv User Manual

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


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

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



Defining the slope

Viewing the slope

Defining the water regime


Using the Reinforcement Manager

Creating the new 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


37

37

37

37



Defining the slope


Defining the surcharge




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


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



Base-sliding resistance

Compatibility with the Advice Note

Pullout resistance


Minimizing soil nail pullout lengths

Special considerations for Two-part slopes

Surcharges


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


Example 3: cutting in stiff clay

Example 5: slip repair in stiff clay

T max

T ob

mechanism

mechanism


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


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


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


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.


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.


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.


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)


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


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.


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.

Print

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


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.


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


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.


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


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.




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.


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.





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









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


 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


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


ReActiv’s title screen appears and, after a few moments, is replaced by the program’s main window, its Frame Window.


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.


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.


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.


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.




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.




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.


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




Since this worked example does not involve a surcharge, the next task is to define the reinforcement.



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.


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.





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.




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.


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:







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.




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:


You will find a copy of the project in its final form in Windows’ Shared Documents folder, located at:


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


ReActiv’s title screen appears and, after a few moments, is replaced by the program’s main window, its Frame Window.


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).


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.





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.





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.




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.






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.


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







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.





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:


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


 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:


 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


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


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.


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


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)


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.


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


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).



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


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.


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).


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


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.

)


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.


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.


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


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.


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


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


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.


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: * = 20E, 8 s

= 1, i = 0, r u

= 0, N = 40E, cN = 0.



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.


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


 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


 X = 22.46m, Y = 0.00m, 2

1

= 55.0E, T max

= 0.00kN/m


B

(despite the rounding mentioned above).

given in the Advice Note


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


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


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


B

given in the Advice Note.


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


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.


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:


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).



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:


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).



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.


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


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


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


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


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


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

Geocentrix 1.7 ReActiv User Manual

Assistant Bot

ReActiv

Version 1.7

User Manual

REINFORCED SLOPE DESIGN

Acknowledgments

Table of contents

Chapter 1

Introduction

About this book

Conventions

Where to go for help

ReActiv’s help system

Tooltips

Technical support

Sales and marketing information

Chapter 2

Installing and running ReActiv

What’s in the ReActiv package

Hardware and software requirements

Upgrading from an earlier version of ReActiv

To install ReActiv

To run ReActiv

Chapter 3

Overview

Job View

Slope

Soil column

Water regime

Surcharge

Datum line

Rulers

Managers

Mechanisms View

Reinforcement View

Toolbar

Status Bar

Soils

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

Printing

Print

Print preview

Customizing the program

Chapter 4

Tutorial 1: embankment in dense sand

Embankment in dense sand

Creating a project

Running the program

Defining the soil

Creating a new soil

Soil properties

Classifying the soil

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