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    MARA UNIVERSITY OF TECHNOLOGY

    CANTILEVER RETAINING WALLDESIGN AND ANALYSISRCWall)

    SuzanaBt Mohd Shaid

    Thesis submitted in fulfillment of the requirements forBachelor of Science Hons) Information TechnologyFaculty of Information Technology AndQuantitative Sciences

    November 2005

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    D E C L A R A T I O N

    I certify that this thesis and the research to which it refers are the product of myownwork and that any ideas or quotation from the work of other people, published orotherwise are fully acknowledged in accordance with the standard referring practicesof the discipline.

    JUNE 17,2006 SUZANA MOHD SHAID2002325807

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    ACKNOWLEDGEMENT

    IN THE NAM E OF ALLAH, THE GRAC IOUS, THE MOST MERCIFUL

    Praised to Allah the Almighty, for all the spirit and strength given to me in order tofulfill the academic requ irements in com pleting this research. I would like to exp ressmy gratitude and appreciation to my supervisor. Prof Ghazali Ahmad, for hissupport and patience. This research was made successful with his guidance andinvaluable knowledge to the research.

    I would also like to express my gratitude to lecturer of Civil Engineering, UiTMShah Alam, for their trust and knowledge. Thanks for providing me all necessaryinformation either directly or indirectly and participating in making this researchpossible.

    Most importantly, to my beloved parents for their everlasting love, inspiration andencouragement all my life and for their supporting role in assisting me to producethis research.

    This gratitude also goes to my beloved husband and my son for his inspiration andmaking this research possible. Thanks for suppo rting me very strongly although I hadto go through some tough times.

    iHan^you verymucd

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    ABSTRACT

    Retaining wall is defined as a structure with a primary purpose to prevent lateralmovement, retain earth or water and may function to support vertical loads. There aremany types of retaining wall and the most common types used are gravity wall,cantilever wall, counterfort w alls, crib wall and buttressed wall. In most design, there aremany types of software available for structural design of buildings. Some of them areEsteem Structural Software, RETWAL and others. Therefore RCW (RetainingCantilever Wall) was developed in order to help the respective engineers to do theirwork much easier and better. In this research, a system is developed using aprogramming application development software Microsoft Visual Basic. To develop thesystem, a prototype methodology is used as a guideline in order to ensure the system isdeveloped in a given time frame. There are a few similar systems that were developedby previous researcher. Both systems provided easiness to reduce users task in designingand analyzing the retaining wall, however this system is developed to be an intelligentsystem. Therefore, a few components need to be used in order to achieve the objective.The interface of this system is designed by using the user-friendly concept. As a result,this system can be used for the design ofacantilever retaining wall. Moreover, it savestime in the design with sufficient layout detail of the cantilever retaining wall.

    IV

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    TABLE OF CONTENTS

    CONTENT PAGE NO.

    TITLE OF PAGEDECLARATIONACKNOWLEDGEMENTABSTRACTLIST OF FIGURESLIST OF TABLES

    1ii

    liiivix

    xii

    CHAPTER ONE: INTRODUCTION

    1.0 Background1.1 Problem Statement

    1.1.1 Current Problem1.1.2 Dev elopm ent Problem

    1.2 Resea rch Aim s and Scope1.3 Obj ective of Study1.4 Resea rch Benefits/ Significance

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    CHAPTER ONE: LITERATURE REVIEW

    2.0 Introduction

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    CONTENT PAGENO .

    2.1 Retaining Wa ll 92.1.1 Lateral Earth Pressure On Retaining Wall 92.1.2 Stability of Retain ing W all 12

    2.2 Existing System or Mo dule of System Retaining W all 142.2.1 CSIDetailer 152.2.2 SEPL-RE TW ALL - Structural Design Software for 16Retaining W alls

    2.2.3 EN VIRO Wall 17

    2.2.4 G E0 4 182.2.5 RETW ALL 20

    2.3 METHODO LOGY APPROACHES 232.3.1 W aterfall 232.3.2 Rapid Application Development (RAD) 26

    CHAPTER THREE: RESEARCH METHODOLOGY

    3.0 Introduction 303.1 Methods of Data Collection 3 0

    3.1.1 Primary Source Data 313.1.2 Secondary Source Data 31

    3.2 Prototype methodology 313.2.1 Planning Phase 32

    VI

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    CONTENT PAGE NO.

    3.2.2 Analysis Phase 333.2.3 Design Phase 33

    3.2.3.1 Logical Design / Process Flow 333.2.3.2 Database Design 373.2.3.3 Calculation Design 383.2.3.4 Screen Design 38

    3.2.3 Programm ing 403.2.4 Implemen tation Phase 41

    3.3 Advan tages in Using Prototype Approach 413.4 Disadvantages in Using Prototype Approach 42

    CHAPTER FOUR: RESULTS AND FINDINGS

    4.0 Introduction 444.1 System Developm ent 44

    4.1.1 Beginning Session 454.1.2 Read File 474.1.3 Ma terial Specification 504.1.4 Soil Parameter 524.1.5 Retaining W all Dimen sion 544.1.6 External Load 574.1.7 Stability Check 594.1.8 Structural Design 604.1.9 Layout and Report 66

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    CONTENT PAGE NO .

    4.2 Comparative Approach4.2.1 Previous Researcher Approaches Excel4.2.2 Advantages and Disadvantages of Using Microsoft

    Excel4.2.3 Advantages and disadvantages of Using Microsoft

    Visual Basic4.3 Conclusion

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    CHAPTER FIVE: CONCLUSIONS ANDRECOMMENDATIONS

    5.0 Introduction5.1 Discussion

    5.1.1 Advantages of the System5.1.2 Lim itations of the System

    5.2 Recommendations5.3 Suggestion for Future Resea rch

    REFERENCESAPPENDICESAPPEN DIX A Gantt ChartAPPEN DIX B Database DesignAPPE ND IX C BS 8110: Structural Use of Concrete

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    LIST OF FIGURES

    FIGURE PAGE NO.

    Figure 2.1 Sketch of design lateral earth pressures on 10cantilever retaining wall for a) internal stabilityand b) global stabilityFigure 2.2 Example screen shot CSIDetailler 15Figure 2.3 Example screen shot SEPL-RETW ALL 16Figure 2.4 Example screen shot ENVIROW ALL 18Figure 2.5 Example screen shot G E04 18Figure 2.6 Example screen shot RETW ALL 22Figure 2.7 Waterfall Model 25Figure 2.8 The Phase of Development Methodology 27Figure 2.9 The Model of Pototyping Methodology 28Figure 2.10 The Model of throw-away prototyping 28Figure 3.1 The Prototype Phases in Developing RCW all 32SystemFigure 3.2 The Work Flow of the System 34Figure 3.3 Work flow for inputting data manually 35Figure 3.4 Work flow for inputting data by open a file 36Figure 3.5 Process flow to produce a report 37Figure 3.6 Layout for Read File Menu 39Figure 3.7 Layout of Main M enu /inpu t form 39

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    FIGURE PAGE NO .

    Figure 3.8 Layou t for Output Presentation (Report)Figure 4.1 Menu to choose input dataFigure 4.2 Main MenuFigure 4.3 Toolbar to know about the systemFigure 4.4 About the systemFigure 4.5 Choose fileFigure 4.6 Display type of fileFigure 4.7 Open data fileFigure 4.8 Form for input Material Specification

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    Figure 4.9 Screen shot of button in Material and SoilParameter interfaces

    Figure 4.10 Form to input Soil ParameterFigure 4.11 Form to input Retaining wall DimensionFigure 4.12 Message box indicate the total dimension of theretaining wallFigure 4.13 Screen shot of button in Retaining W allDimension and External LoadFigure 4.14 Form to input External loadsFigure 4.15 Message box displayed the height of backfillabove footingFigure 4.16 The system displayed the stability checkFigure 4.17 Form to input Main Steel Bars (colored in gray)

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    FIGURE PAGE NO.Figure 4.18 Form display information and set input for user 61needFigure 4.19 Combo box for Steel Bars and Spacing Bars 63Figure 4.20 Curtailment of Main Reinforcement 64Figure 4.21 Deflection of Main Reinforcement 65Figure 4.22 Layout of RCW all 67

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    LIST OF TABLES

    TABLE PAGE NO.

    Table 4.1 Desc ription of input field in Material SpecificationTable 4.2 Desc ription of input field in Soil Param eterTable 4.3 Desc ription of input field in Soil Param eterTable 4.4 Desc ription of input field in Soil Param eterTable 4.5 Desc ription of input field in Ma in Steel BarsTable 4.6 Desc ription of input field in Secondary Steel BarsTable 4.7 Desc ription of input field in Curtailment ofReinforcement

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    CHAPTER ONEINTRODUCTION

    1.0 BACKGROUND

    The Concrete Cantilever Retaining Wall can be defined as a constructed ofreinforced concrete to support backfill soil by a cantilever action. The base slabserves as a permanent support and prevents against overtunning and sliding. Thecantilevered stem portion is rigid at the bottom and is free at the top . A key can bean option to be installed at the bottom of the base slab. This is to ensure extrasafety against the sliding. The walls will provide long-standing stability andserviceability. This type of concrete is widely used because of the easiness inconstruction and cost-effectiveness.

    Due to the rapid development of increasingly powerful computers in the lastdecades, the solution of rather complex multi-phase problems encountered inwidely different fields of engineering tasks is feasible nowadays. Nowadays, thenum bers of software in the market is growing. Software is developed to help usersin making their task easier. We can find different software for different businessprocess. In Geotechnical E ngineering, there are few software that can be bought inthe market. For example RETW ALL Software, SEPL-RE TW ALL, GeoStudioand many more.

    Therefore, this study will focus on developing an Analysis and Design ofReinforced Concrete Wall. This system is developed to help GeotechnicalEngineers to analyse and design the structure of retaining wall. There are a fewtype of retaining wall. This study will only focus on developing a system for the

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    analysis and design of reinforced concrete Cantilever retaining wa ll. In order to dothat, Geotechnical Engineer must adapt their previous methods, procedures andstandards. This move requires changing existing roles, such as that of the dataanalyst and drawing of the structure.

    Moreover this system will be designed to help the Geotechnical Engineers to maketheir task or method easier than the current system. This system also allows theusers to store, retrieve and produce a design report. It is designed as an stand-aloneapplication and needs to be instaledl in the engineers personal com puter in order torun the system. In ad dition, it will provide 3 major functions for users such as dataanalysis, retaining wall design and production of report. Besides that this systemalso provides 2 easy ways for the user to input data, where users can choosewhether to input the data manually or by giving a file that contain data for thesystem to retrieve the input. This system is designed to read in 2 different formats,which are excel and tex t file.

    1.1 PROBLEM STATEMENT

    This system is developed for the Faculty of Civil Engineering, UiTM Shah Alam,based on the existing system that had been developed by previous researcher.Some problem have been detacted during the research period. Which are definedinto 2 categories, include current problem and developm ent problem .

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    1.1.1 C ur ren t Problem

    For the time being, the analysis and the design of retaining wall is done manuallyor by using limited trial softwares. At present, user conduct their analysismanually, initialising the analysis up to the structural design. Previous researcherhad developed the same system by using Microsoft Excel as the software tool,though there is an existing system, the analysis and design manually is still beingadopted. The use of advance technology gives an alternative way to solve theanalysis and design problem. In order to upgrated the existed version, this systemis developed using Microsoft. Visual Basic and Microsoft. Access as a database.

    Based on the analysis done on the previous system, there are some problems thathave been faced by the users to do the analysis and designing of the retaining wall.Below are the problems that w ere identified:

    i. The calculation done is done manually and sometimes can cause error, dueto the complexity of the calculation.

    ii. The existing system does not store data and it can only be retrieved from theuser.

    iii. Besides that, the existing system sold in the market are too expensive. As aresult most of the lecturer in the faculty of Civil Engineering prefer to usethe trial version software that can be downloaded from the internet for free.

    1.1.2 Dev elopm ent Pro blemThis new system will provide different facilities to users. The new system willprovides an option to the user in choosing different ways in inputing the data eithermanually or by allowing the system to extract data from a given file. Besides that,

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    the output presentation of the new system allows users to save the report in 2different format, either as an Adobe Acrobat or Microsoft Excel . This is a majorproblem that occurs during the development period, whereby the problem ofconverting the result to different format appears. When using Visual Basic as aprogramming language, a few errors have been encountered.

    i. Missing components in the MSDN library. This error occurs when theprogram is accessed to retrieve in the other computers which have astandardjnstallation of Microsoft Visual Basic. The missing libraries areMs Excel 10.0 Object Library, BbAcceleratorSGRIDID 6.vbalGrid. This isdue to the third party component. This additional component need to beinstall and save in the same directory as the system. For example create anOCX folder in the system folder for the ocx file in order to make sure thesystem is running smoothly.

    ii. Different techniques need to be used to input data into the Excel file and toobtain the data from the Excel archive file. The formula for the thecalculation design is written is the visual basic code. The output will beintegrated into Excel file.

    iii. A few components need to be installed in order to develop this system basedon the time constraint. The components have to be downloaded from theinternet in order to save cost and time.

    iv. In order to develop a flexib le system, this system is designed to provide userwith an opportunity to choose from different format to save the output orreport. This system allow s users to save report or output in 2 different formatwhich is or Excel and Acrobat reader format. Therefore some of the thirdparty components have to be installed. A few ocx file have to be search inorder to provide this funtion to the users.

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    1.2 RESE AR CH AIMS AND SCOPE

    This research focuses on developing and enhancing the existing manual system.This system can do analysis and design of Reinforced Concrete Wall. This systemis developed using Microsoft Visual Basic 6.0. Although, Reinforced ConcreteWall had a different type of retaining wall, but this study focus only on theReinforced Cantilever Concrete Wall.

    The research aims are to redesign and to enhance the existing system by using theVisual Basic 6.0 software. The existing system is developed using the MicrosoftExcel.

    This research will focus on the following aspects :

    i. New features that can provide information and give guidance to user. Inorder to do that, a few vb tools need to be used that can help to improve thedocument performance.

    ii. Provide effective processflow in order to ensure the sytem is user friendly.

    iii. Output presentation in pdf or excell format.

    iv. The system can define (read and write) data in different formats ( forexample excess to excell). Therefore, the system can be categorized as aflexible system.

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    1.3 OB JEC TIV E OF STUDY

    The objectives of building a Analysis and Design of Reinforced Concrete Wallare :

    i. To simplify the users work in designing the retaining wall manually.

    ii. This system will provide an easier way for user to input the data. The userscan choose whether they want to input the data manually or let the systemretrieve the data from a given file. This system will do the calculation for theuser, and as a result the system will automatically produce the design of theretaining wall to the users.

    iii. To develop the system according to the British Standard 8002:1994 andBritish Standard 8110:1985. British Standard 8002:1994 is a code practicefor earth retaining structures. It include sufficient information on the groundwater conditions with the strength and deformation properties of the soilwhich will be retained and the soil which will support the earth retainingstructures. (S.S Cue Y.C. Tan (1998)). Meanwhile Brifish Standard8110:1995 is a code of pracfice for Structural Use of Concrete. It isimportant to refer to the code of pracfice order to produce a useful system.

    iv. To simplify the analysis and design. This system will do all the calculationsfor the users. The calculation are hidden from the users interface. Thissystem will take the input and calculate it to be used for the analysis anddesign of the retaining wall.

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    1.4 RESE AR CH BEN EFITS/ SIGNIFICANCE

    In geotechnical firm, software like RET WALL is used widely for design andanalysis. Although there are a few softwares seen in the market, the cost is tooexpens ive. Therefore from this research, it is beneficial for the developm ent of thissystem, which em ploys both structural and civil works.

    The contributions of this system are:

    i. This research will benefit the Geotechnical Engineers, where this systemwill simplify their massive task. The sytem is developed for the ready-to-use concept. That means users need to key-in the input and the systemwill generate the calculation automatically for the result.

    ii. In addition, it is also an alternative software to many other softwaresavailable in the market. This is an effort to contribute to the developmentof Geotechnical Software.

    iii. Lastly, this system will save cost of buying the existing system in the marketthat is too expensive. This system is developed in house and as a result itwill be cheaper than the others.

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    CHAPTER TW OLITERATURE REVIEW

    2.0 INTRODUCTION

    Geotechnical engineers often participate in the design of retaining wall (alsoknown as earth retaining structures). The design of the wall must resist slidingalong its base, resist overturning, not exceed the bearing capacity of the soilbeneath the base, avoid excessive settlement and built structurally strong toresist failure fi-om the build up of internal stresses produced by external forces.There are two categories that are near- vertical or vertical wall that help toretain soil or rock. Retaining w alls provide permanen t lateral support to verticalor near-vertical slopes of soil. Different kinds of retaining structure each suitedfor particular applications. In construction operation, it is necessary to alter thegroimd-surface profile in such a way as to produce vertical or near-verticalfaces.

    Nowadays, computer does the entire complicated job for us. This is what wecall towards the Information Technology world. Most of the expert workers'task is done by a computer. Information Technology and computer play a bigrole in assisting the knowledge expert do their job easier. A lot of softwarehave been designed to assist these knowledge expert workers to do their task ina more effective and efficient way.

    In order to design or develop software of retaining wall, some calculationneeds to be done. Traditionally, the engineer had done the calculation andplotted the graph manually. But nowadays, there are a few of software that arealready designed or developed in order to help geotechnical engineers to do thecomplicated task.

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    2.1 RETAINING WALL

    Retaining w alls are built to hold back soil ma ss. How ever, it can also beconstructed for aesthetic landscaping purposes. There are four (4) types ofretaining wall that are commonly used in construction project, which areCantilever retaining walls, Cou nterfort retaining walls, G ravity retaining w allsand Semigravity retaining walls. Cantilever retaining walls are made ofreinforced concrete that consists of a thin stem and a base slab. This type ofwall is economical to a height of about 8m. Although Counterfort is similar tocantilever wall, at regular intervals, they have thin vertical concrete slabsknown ascoun terforts that tie the wall and the base slab together. The purposeof this retaining wall is to reduce the shear and the bending moments.

    Next are Gravity retaining walls, with plain concrete or stone masonry. Itdepends on their own weight and any soil resting on the masonry for stability.This type of retaining wall is not economical for high walls. Semigravityretaining walls are similar to Gravity retaining walls, but a small amount ofsteel may be used for the construction of gravity walls. It minimizes the size ofwall section.

    2.LI Lateral Ea rth Pressure On Retaining WallTo design retaining wall, an engineer must know the basic soil parameters.These include the unit weight, angle of friction and cohesion of the soilretained behind the wall and the soil below the base slab. Knowing theproperties of the soil behind the wall helps the engineer to determine the lateralpressure distribution that has to be considered in the design. The design of aretaining wall process occurs in two phases. O'Rourke and Jones (1990)classified retaining walls into two broad categories: externally stabilizedsystems and internally stabilized systems. Externally stabilized is checked for

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    stabil i ty, including from possible overturning, s l iding and bearing capacityfailures.While the second category is to check for adequate strength and steelreinforcement for each component.

    It is vital to find out the loads and pressure stand-in on the retaining wall beforeany retaining wall can be designed. The primary function of the retaining wallis to resist the load. Contrary to the design of massive gravity retainingstructures, the design of canti lever retaining walls requires the considerat ion ofboth internal and global stability.

    a arth pressures on stemofth e wall b arth pressures on heel section

    stemsection \strucmral

    s t e m - I M ; ; : ; : - i x ; ; : ; i x b lo ck

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    Figure 1.Sketchof design lateraleanh pressures on cantilever retaining wallfor a internal stabilitj' a n db globalstability.

    Figure 2 .1 : Sketch of design lateral earth pressures on canti lever retaining wallfor a) internal s tabil ity and b) global stabil i ty (W.I. Cam eron R.A . Green)

    Cameron and Green classif ied that the global stabil i ty of canti lever retainingwall, the lateral earth pressures are assumed to act on a vertical section (or heelsection), which extends from the heel of the wall through the backfi l l to thegrovmd surface. It is a standard design practice to assume that the critical earthpressures for global and internal stability of cantilever retaining structures aresynonymous. For global stabil i ty evaluations, the cri t ical load case corresponds

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    to the dynamic pressures in which those are imposed on the wall as it movesaway from the backfill such as active condition. For internal stabilityconsidera tions, recent studies (Green Ebe ling 2002 , Green et al. 2003) haveshowed that higher pressures act on the wall as it moves towards the backfill,which is of no concern for the global stability of the wall, but constitutes thecritical load case for internal stability.

    There are certain theory and assumptions used to determine the pressure actingon retaining walls. The most popular or common theories are Coulomb earth-pressure theory (1776), Rankine theory (1857) and Terzaghi and Peck'smethod (1967).

    The Coulomb theory (1776) outlined that:

    i. The soil is an isotopic, hom ogeneous with internal friction and cohesion .

    ii. The rupture surface is a plane surface but Cou lomb suspected that thesurface might be curved.

    iii. The failure surface is rigid.

    iv. There exist wall frictions.

    V. The failure surface for the active pressure is at certain angle from thehorizontal plane and the horizontal backfills the angle are independent ofthe soil cohesion.

    While in Rankine theory (1 857), where he stated that:

    i. Soil is isotopic and hom ogeneou s (similar to Coulom b theory ).

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    ii. The surface is the most critical shear where in reality; the surface isslightly concave up

    iii. The wall is infinitely long and the problem can be analyzed in twodimensions only. (Geotechnical engineers called it plane straincondition).

    iv. Active and passive conditions are developed by the wall movem ent.

    There are three most important soil conditions, which are at rest condition,active condition and passive condition. At rest condition means, the wall is tobe rigid and unyielding. The wall does not move, even small movement altersthe lateral earth pressure. If a wall structure is caused to move towards the soilbeing supported, the horizontal pressures in the soil will increase. This isreferred topassive pressures. If the wall moves away from the supported soil,the horizontal soil pressures will decrease. This is referred to active pressures(O'Rourke and Jones (1990).

    2.1.2 Stability of Retain ing Wall

    The purpose of design is that the retaining wall needs to be stable in allconditions. The conditions include horizontal sliding of the wall, the overturn,normal facing act on the base of the footing within the middle third of thefooting, the foundation with the bearing capacity and the wall must undergo adeep-seated failure. For each of these conditions, the stability depends on,thedimension and forces acting between the wall and the ground. When evaluatingstability, the soil unit must be taken into consideration.

    The sliding of the retaining wall is evaluated by using a limit equilibriumapproach (Sokolovsky, 1960). The guidance in sliding stability is based onconventional geotechnical principles of limit equilibrium. The basic principleof this method applies the factor of safety to the least known conditionsaffecting sliding stability, this is, the material shear strength (EM 1110-1-2908,