Greta Oasys Geo Suite for Windows
Contents
1. Prior to analysis the program carries out a data check The data checks carried out are as follows e The material layers beneath the base slab are the same between the front and back e The anchors are all placed at or below ground level and above the top of the base H no errors are found then the calculation can proceed Select OK Note The option to Delete results becomes available once the calculations have been completed Oasys Ltd 2014 43 Greta Oasys Geo Suite for Windows 4 2 Tabular Output Tabular Output is available from the View menu the Gateway or the Greta toolbar The results are provided in both a full and condensed tabular form The lists of tabulated output can be highlighted and then copied to the clipboard and pasted into most Windows type applications e g Word or Excel The output can also be directly exported to various text or HTML formats by selecting Export from the File menu Ei GretaManual grw Tabular Output NOTES Greta example file RESULTS SOIL AND WATER PRESSURES FOR OVERALL STABILITY Pressures on virtual back surface Interface Location Strata Level Soil Pressures Water Pressure Upper Lower mOD kN m kN cm kN m 0 Ground level D 5 40 00 8 80 00 l Top of base 1 0 40 27 50 27 50 00 2 Bottom of base 00 29 00 29 00 00 Pressures on virtual front surface Interface Location Strata Soil Pressures Water Pressure Upper Lower EN m IEN cm IEN cm 0 Ground level 00 002. from the Data menu or the Gateway Oasys Ltd 2014 Overall Stabilit Bending Moment Calculations N m N m 0 00 H only one data point is entered for either side of the wall the program will assume a hydrostatic groundwater distribution on that side of the wall The pressure specified at the point need not necessarily be zero For the first point on each side of the wall the unit weight of water must also be entered For hydrostatic distributions the water pressure u is calculated from U Zei Where z iS depth below water table level and Ywis specified unit weight of water Thus a partial hydrostatic condition can be modelled by specifying a value of y less than 10kN m Note All defined water pressures are assumed to extend laterally from either side of the wall For piezometric profiles the level and pressure at each known point must be entered If more than one data point is entered the program will assume that the points represent piezometers and the groundwater pressure will be interpolated vertically between the specified points Below the lowest point groundwater pressure will be assumed to extend hydrostatically The groundwater pressure beneath the base slab is assumed to have a linear profile between the elevations at the front and back Groundwater flow beneath the wall is not modelled 3 3 8 Surcharges Uniformly distributed surcharges can be placed on the surface of the soil on either si
3. 00 l Top of base 00 00 00 2 Bottom of base 00 00 00 Vertical component forces Component Force Moment kN m ENn mx Weight of wall 63 45 81 08 Weight of soil 148 75 316 09 Shear on virtual back 00 00 Oasys Ltd 2014 4 3 Graphical Output Graphical output is accessed via the vew menu using View Graphical Output the Gateway or the Greta Toolbar Greta 19 1 fa_Manual grv File Edit View Data is Tools Window Help Overall Stabillity N structural calculations Limiting KO pressures Structural calculations Compaction pressures File Edit View Data Analysis Tools Window Help WOW aala alae HIRE X 2 HE r Aa aA omr NM SK MP tT A ba L d Overall stability Structural calculations Limiting KO pressures Structural calculations Compaction pressures Oasys Ltd 2014 CR Greta Oasys Geo Suite for Windows GretaManual grw Overall Stability 3 6 000 2 000 2 000 Scale x 1 176 1 176 Overall Stability The graphical representation of the soil layers the retaining wall and surcharges is shown here This window has a toolbar which has buttons corresponding to different physical quantities like active and passive pressures pore water pressure soil layers and bending moment and shear force diagrams When the user makes the appropriate selection the corresponding plot is shown The plot can be exported in WMF f
4. Oasys Ltd 2014 Greta Oasys Geo Suite for Windows 2 1 1 Overall Stability The calculations for overall stability use the soil pressure profiles derived for the virtual boundaries on back and front of the wall Virtual a Front Line udl Load Phreatic Surface ul Surchar I Reg x 3 I I Full active and passive earth pressures are calculated to determine the overall equilibrium of the wall For the soil behind the wall the active earth pressure is calculated using the soil coefficients k and k The passive pressures in front of the wall are calculated using the corresponding values of kp and Kpc The vertical components of friction and adhesion for the front and back are also included Soil and water pressure profiles are calculated for the full depth of the wall including the shear key if present These forces are used in the check for sliding and determination of the area and pressure in the stress block Vertical forces General Back Front Weight of wall Weight of soil above heel Weight of soil above toe including key Shear on virtual back Shear on virtual front Anchor forces Shear on back of base Shear on front of base Water pressure under Oasys Ltd 2014 Methods of Analysis e base Line load on top of wall Note Vertical shear forces for the depth of the shear key and surcharges confined by the area of the base are not included Horizontal forces General Ba
5. Greta 6 46 Assembling Data 27 Greta Toolbar 2 B Ground Anchors 4 Ground Water Pressures 4 Groundwater 37 Base Slab 35 H Bearing Capacity 1 10 Bending 15 16 Bending Moments and Shear Forces 16 Heel 4 7 33 C Horizontal 7 Horizontal Forces 11 Hydrostatic 37 Components of the User Interface 2 D Increments 16 Data Input 30 Intermediate 19 Deformation 10 Intranet Link And Emails 29 Descriptions 34 K E Key 4 7 15 Earth Pressures 19 L Email 29 Equilibrium 15 46 Example 46 Line Load 4 7 38 Excel 43 M Material Layers 35 Oasys Ltd 2014 Material Properties 34 Middle 7 Moment 15 N Net Force 15 Number of Sections 33 O Opening the Program 27 Overall Equilibrium 7 Overall Stability 1 6 7 10 20 46 P Passive 7 11 34 46 Phreatic 19 Piezometers 37 Plastic 10 Plastic Stress Block 10 R Resultant Force 46 Rotation 1 11 46 S Screens 30 Shear Forces 6 Shear Key 10 11 15 Shores 39 SI 32 Sliding Check 10 Sliding Resistance 10 Soil Coefficients 4 Soil Strata 4 Standard Toolbar 2 Static Equilibrium 1 Stem 1 33 Stress Block 7 Structural Design 1 Structural Types 4 Struts 39 Oasys Ltd 2014 Support 29 Surcharges 7 38 T Table View 2 Tabular Output 2 43 Tapering 4 Titles 31 Titles Window Bitmaps 32 Toe 4 33 Toolbar 2 U Underside 35 Uniform Surcharges 4 Units 32 Unstable 7 11 User Interface 2 V Vertical Forces 11 Vertical S
6. anchor on front face of wall Each anchor can hawe a separate force applied for analysis of overall stability and Bending moment calculations A single angle to the horizontal is required Anchor forces can also be used to represent forces in shores and struts Note Users must satisfy themselves independently that the anchor systems are capable of sustaining the specified forces 3 3 10 Base Optimisation Tool The base width optimisation for optimum utilization of external properties can be carried out using the base optimisation tool this can be accessed by clicking the X on Greta toolbar or from Tools Optimise base from Data menu Oasys Ltd 2014 a Greta Oasys Geo Suite for Windows Optimise Base Slab Width Initial Geometry of Wall Distance From toe to ae front of wall stem 0949995 m Optimise Distance of heel to SS back of wallstem 11775 m Optimise Resultant within 1 3 of base width Optimized Geometry of wall Distance from toe to 125 amp Command Calculate Optimize FullBase A e Optimize Heel Only Distance of heel to 1 76800C m Optimize Toe Only a Front of wall stem back of wall stem Recalculate Mi Comparison of checks Case Force Resistance FOS Remark Overall Stability Bearing Pa 131 89 1911 83 14 5 Pass Sliding N 102 05 122 51 Pass Overturning Nm 226 46 397 17 1 75 Pass Uplift Ny 212 20 Pass Base 3 00m Heel 1 75m toe 0 95m Overall Stabil
7. component and H as horizontal component The effective width of the foundation is such a way that its geometric centre coincides its load centre or the width of the plastic stress block i e if the vertical component intersects the base at a distance a from the toe then the width of the base is 2a Oasys Ltd 2014 Methods of Analysis 22 Calculation of unit weight y The unit weight of the soil used in the bearing capacity equation depends on the position of the water table lf the water table is at a depth of more than twice the total width of the foundation then dry unit weight of the material is used However if the water table is at a depth of less than 0 5 times the total width of the foundation then buoyant unit weight of the soil is used Between 0 5 and 2 times the foundation width the unit weight varies linearly from buoyant unit weight to saturated unit weight Bearing capacity computation methods In Greta the following methods are used for calculation of bearing capacity Brinch Hansen 1970 Drained undrained analysis E7 Annex D D3 Undrained analysis E7 Annex D D4 Drained analysis Meyerhof Drained analysis Note For all these computation methods the unit weight used in the N terms is calculated as follows When the groundwater is at or above 0 5B below the base saturated unit weight and buoyant weight are used When the groundwater is at or below 1 5B below the base non saturated unit weight
8. drop down menus provide alternative units with their respective conversion factors to metric Standard sets of units may be set by selecting any of the buttons SI kN m kip ft kip in Oasys Ltd 2014 33 Greta Oasys Geo Suite for Windows Once the correct units have been selected then click OK to continue SI units have been used as the default standard throughout this document 3 3 3 Analysis Options The analysis options allows the user to specify the number of sections down the stem of the wall and along the toe and heel of the base to be taken for calculation of the shear forces and bending moments Include derivation of bending moment calculations Calculation points Number of increments down wall Number of increments along toe section Number of increments along heel section Method for calculating soil pressures behind wall Factor to be applied to Ka pressures Compaction pressures based on CIRIA design guidance on modular gravity retaining walls Calculate bending moments using compaction pressures Method for calculating compaction pressures Automatic Effective line load per metre of roller kN Zen Critical depth for compaction pressures KN r Depth where compaction pressures remain significant m pp ly U n d Oo If the box for Include derivation of Bending moment calculations is checked then the calculation for shear forces and bending moments will proceed Otherwise they w
9. is used and no buoyancy is considered When the groundwater level is between 0 5B and 1 5B interpolate linearly between the above two values Brinch Hansen 1970 Drained analysis In this method only drained conditions are considered Ui 0 5 YB N si dy AN Salaga Undrained analysis U it n 2 c 1 8 E 9 Bearing capacity factors N N 1 tan o N tan 45 q 2 er ar N 1 5 N 1 tan A Shape factors Oasys Ltd 2014 23 Greta Oasys Geo Suite for Windows S 1 0 4 BYL S 1 sin f BYL Since B lt lt L the above equations reduce to Load inclination factors i 0 5 0 5 1 0 min 1 0 H A e ul i 1 0 5 H V A c cot OI i 1 0 7 H V A e cot gf V net vertical force acting on the wall H net horizontal force acting on the wall A effective area of the foundation effective width length Ground inclination factors J 8 147 g D 0 5 tan p gt g 1 0 5 tan p gt B angle of inclination of sloping ground in front of the wall EC7 Annex D D3 Undrained analysis In this method only undrained conditions are considered U oN sig 9 ccc Bearing capacity factors N n 2 5 14 c Shape factors s 1 0 2 B L Oasys Ltd 2014 Methods of Analysis a Since B lt lt L the above equation reduces to Sc Load inclination factors i 0 51 d H A c H net horizontal force ac
10. modifying the value assigned to the strength of the soil in front of the wall Vertical forces General Back Front e Weight of wall including e Weight of soil above heel e Weight of soil above key e Shear on back of wall toe e Anchor forces e Shear on back of base e Shear on front of wall e Water pressure under base e Surcharge above heel e Shear on front of base e Line load on top of wall e Soil pressure inclined back e Surcharge above toe e Water pressure inclined back Note Vertical shear forces for the depth of the shear key are not included Horizontal forces General Back Front e Anchor forces e Soil pressure on back of e Soil pressure on front of wall wall e Water pressure e Water pressure e Shear force inclined front e Shear force inclined back Oasys Ltd 2014 13 Greta Oasys Geo Suite for Windows Active Eat Cc CH g ud a st Pressure Water Pressure Pressure Base friction adhesion Base friction adhesion The total horizontal and vertical forces are resolved to provide an overall resultant force The location of the intersection of the force with the base is given including whether the force is located within the middle 1 3 or outside the area of the base Unstable configurations are as for the overall stability calculations see Overall Stability The soil and water pressure profile beneath the base is calculated as follows If the eccentricity is within the
11. phi 33 c 0 delt beta 20 gam 18 Wen 2 Computation method Bech Hansen 1970 Surcharges Notes 5 Anchor Loading 0 Jee Brinch Hansen ground incination facte 2 Qac XR Greta Manual example Graphical k CIkN n Overall Stabity gd unbedengt d GretaMan grw Analysis Options C GretaMan grw Tabular Output S Inchide derivation of bending moment calculations a f See z s Tabular output Calculation points Gateway Number of increments down wall Number of increments along toe section Number of increments along heel secon Method for calculating sol pressures behind wall Factor to be applied to Ka pressures SOIL AND WATER PRESSURES FOR BENDING MOMENT CALCULATIONS Using at rest acti Compaction pressures based on CIRIA design guidance on modular gravity retaining walls Pressures on back face of wall E GretaMan grw Material Properties SEE 4 GretaMan grw Overall Stability Material Properties table view Graphical output Phi Cohesion i 1 28 Page General Cola For Help press FL 1 2 1 Working with the Gateway The Gateway gives access to all the data that is available for setting up a Greta model Top level categories can be expanded by clicking on the symbol beside the name or by double clicking on the name Clicking on the symbol or double clicking on the name when expanded will close up the item A branch in th
12. tabs at the bottom of the table and clicking the left mouse button Material Properties for Overall Stability Manual grw Material Properties 4 gt General Overall Stability Bending Moment Calculations Page Overall Stability Cell A 1 Material Properties for Bending moment calculations Oasys Ltd 2014 35 Greta Oasys Geo Suite for Windows Manual grw Material Properties qj General A Overall Stability Bending Moment Calculations EJ Page Bending Moment Calculations Cell A 1 Overall stability Bending moment Description calculations Virtual boundary Soil Wall friction Angle of friction in degrees friction Virtual boundary Soil Wall Adhesion c adhesion adhesion ka k Active earth pressure Kac k Active earth pressure due to cohesion kp Kow Passive earth pressure Koc Kow Passive earth pressure due to cohesion On occasions the user may wish to model an excavation in front of the wall This can be achieved by including a soil type Ai in front of the wall Parameters chosen should use a minimal bulk unit weight e g 0 01 KN m3 low shear strength e g 1 00 and coefficients K e g 0 1 This will help to provide minimal passive resistance in front of the wall 3 3 5 Material Layers The level of the base of each material layer must be entered The levels can be different on either side of the wall only to the level of the underside of the base slab Material Lay
13. vertical effective overburden pressure v Note Modification of the vertical effective stress due to wall friction should be made by taking appropriate values of k and kp k and kp k and Ka cohesive coefficients of active and passive pressure horizontal coefficients of active and passive pressure Note For conditions of total stress ka kp 1 For a given depth z z Ty ID Tryg TU 0 Where Ys unit weight of soil u pore water pressure Oud vertical sum of pressures of all uniformly distributed loads udls above depth z A minimum value of zero is assumed for the value of kd k Cc Alternatively the user may also choose to consider at rest pressures behind wall In this case the pressure behind wall is calculated as Oasys Ltd 2014 Methods of Analysis k is the coefficient of earth pressure at rest Another option is for the user is to use average of at rest and active pressures behind wall In this case the average of the above two values is used The last option is to apply factored ka pressures In this case the active pressures are initially calculated as explained above Then they are factored by a user defined factor 2 1 3 1 Friction and adhesion Stresses due to friction are calculated are the virtual and front of the wall for assessment of overall stability and at the wall surface for calculation of the forces in the stem and base Based on Section 9 5 1 6 Euroc
14. GRETA Version 19 1 Oasys Oasys Ltd 13 Fitzroy Street London W1T 4BQ Central Square Forth Street Newcastle Upon Tyne NET 3PL Telephone 44 0 191 238 7559 Facsimile 44 0 191 238 7555 e mail oasyS arup com Website http www oasys software com Oasys Ltd 2014 Greta Oasys Geo Suite for Windows Oasys Ltd 2014 All rights reserved No parts of this work may be reproduced in any form or by any means graphic electronic or mechanical including photocopying recording taping or information storage and retrieval systems without the written permission of the publisher Products that are referred to in this document may be either trademarks and or registered trademarks of the respective owners The publisher and the author make no claim to these trademarks While every precaution has been taken in the preparation of this document the publisher and the author assume no responsibility for errors or omissions or for damages resulting from the use of information contained in this document or from the use of programs and source code that may accompany it In no event shall the publisher and the author be liable for anyloss of profit or any other commercial damage caused or alleged to have been caused directly or indirectly by this document This document has been created to provide a guide for the use of the software It does not provide engineering advice nor is ita substitute for the use of standard refere
15. Program Description Greta is used for analyzing gravity retaining walls It performs two calculations which assess the overall stability of the wall and the forces in the stem and base The calculation for Overall stability examines the static equilibrium of the wall The program assumes that full active and passive soil pressures develop on the virtual boundaries behind and in front of the wall respectively The wall is assumed to act as a rigid body together with any soil encompassed by the vertical planes through the extremities of the base The total horizontal and vertical forces are resolved to calculate the force on the base of the wall The required reaction of the foundation soil is then calculated to provide equilibrium of the wall The location of the resultant force is also checked and reported If the rotation of the wall due to the applied force is towards the heel then the calculation is stopped The program also calculates the horizontal component of load on the wall and the sliding resistance of the foundation The user can specify separate shear strength parameters for the foundation soil to those used for creation of the active and passive pressures The program also calculates the bearing capacity of the foundation and check it against the stress developed in the soil below the base Application of factors to loads or soil strengths to assess the factor of safety of the wall is at the discretion of the user The calcula
16. cally Automatic saving can be disabled if required by clearing the Save file check box Show Welcome Screen enables or disables the display of the Welcome Screen The Welcome Screen will appear on program start up and give the option for the user to create a new file to open an existing file by browsing or to open a recently used file Company info The company information button in the preferences dialog box allows external companies to specify the bitmap and Company name that they would like to appear the top of the printed output Oasys Ltd 2014 About Greta 4 Company Information Enter the full path of the bitmap file that you would like to appear on your printed output The bitmap will be fitted into a space approximately 4 cm by 1 cm but its aspect ratio will be maintained Select the company name that you would like to appear lt blank gt on your printed output l To add a bitmap enter the full path of the file The bitmap will appear fitted into a space approximately 4cm by 1cm The aspect ratio will be maintained Note For internal Arup versions of the program the bitmap option is not available Page Setup Opens the Page Setup dialog allowing the style of output for printed text and graphics to be selected If Calculation Sheet Layout is selected the page is formatted as a calculation sheet with details inserted in the page header If Logo is selected the company logo is inserted in the to
17. case the user has to manually calculate the bearing capacity of the foundation and check whether the induced vertical stress is within permissible limits For information on calculation of bearing capacity please see Bearing capacity 2 1 2 Bending Moment Calculations The calculations for bending moment calculations use the soil pressure profiles derived directly on back and front of the wall Line Load udi Surcharge udl Surcharge emea Surface Oasys Ltd 2014 Methods of Analysis 12 For the soil behind the wall the active earth pressure is calculated using the soil coefficients Kaw and Kuer These values should allow for compaction stresses where appropriate The passive w These values are not necessarily the passive pressure coefficients of the soil but can be used to define the stresses the user wishes to be applied to the front of the wall pressures in front of the wall are calculated using the corresponding values of Kow and Koc Soil and water pressure profiles are calculated for the full depth of the wall including the shear key if present These forces are used in the calculation of the pressures beneath the base of the wall and the shear force and bending moments in the stem and base The horizontal soil pressures underneath the base are taken at the virtual boundaries In reality the restraining force available from a shear key may be greater than this The user may choose to model this effect by
18. ck Front Anchor forces Soil pressure virtual back Soil pressure virtual front Water pressure Water pressure Virtual Ang Front Friction Adhesion Boundary Friction Adhesion Active Eartr Pressure Water Pressure Pressure I Base friction Base frictior adhesion adhesion The total horizontal and vertical forces are resolved to provide an overall resultant force The location of the intersection of the force with the base is given including whether the force is located within the middle 1 3 or outside the area of the base Unstable configurations for the wall would be Oasys Ltd 2014 Greta Oasys Geo Suite for Windows Line of action of resultant force lies outside base Distance Y is calculated and reported XR y F Resultant vertical applied force is upward e Uplift The calculation is also stopped if the rotation of the wall is towards the heel Resultant force lies beyond the centre line of the base Wall rotation towards heel In this situation the active and passive pressures will be reversed and therefore the given calculation becomes invalid Further the calculations are terminated if the restoring passive force on he virtual boundary is greater than the disturbing active force i e the the net horizontal force is negative In this case the wall has the potential to slide backwards thereby contradicting the assumptions about the active and pa
19. de of the wall A line load can also be placed at the centre line of the wall stem Surcharges dialog can be invoked by selecting Surcharges from the Data menu or the Gateway Oasys Ltd 2014 Greta Oasys Geo Suite for Windows fa da manual 19 1 0 9 grw Surcharges All vertical uniformly distributed loads Overall stability Behind wall 40 0 Along top of wall 0 In front of wall Extend surcharge across the footprint of foundation for overall stability case also Bending moment calculations Behind wall 40 Along top of wall 0 In front of wall i Ap D ly U nd O KN dng kN m KN rr kN dng kN m kN dng H the check box for surcharge extension is checked then the surcharge above the toe and heel portions is included in the calculation of net bearing capacity Different surcharges can be specified for the overall stability case and bending moment calculations case 3 3 9 Anchor Loading Anchors can be placed in the stem below the ground level at the back of the wall and above the top of the base slab Anchors can be entered in tabular form by selecting Anchor Loading from the Data menu or the Gateway Oasys Ltd 2014 E manual 19 1 0 9 grw Anchor Loads Levelat Angelo Force kN m i ___ front of wall horizontal _Overall_ Bending Moment fmOD Deg Stability Calculations eege S Location of head of
20. detail in Bearing Capacity For all these computation methods the unit weight used in the N terms is calculated as follows When the groundwater is at or above 0 5B below the base saturated unit weight and buoyant weight are used Oasys Ltd 2014 Greta Oasys Geo Suite for Windows When the groundwater is at or below 1 5B below the base non saturated unit weight is used and no buoyancy is considered When the groundwater level is between 0 5B and 1 5B interpolate linearly between the above two values FoS Data The user then has to specify the factors of safety to be used in calculation of bearing sliding and overturning scenarios d Greta_BearingCapacity grw Fou DER Soil Structure interaction Allowable Soil Base Friction deg Allowable Soil Base Cohesion kN m2 Bearing Capacity of foundation Carry out bearing capacity calculations Material fill Drainage Drained Computation method Brinch Hansen 1970 C kN r Phi deg Density kN Are F 0 5 to be used Bearing Sliding Overturning 3 3 7 Groundwater Groundwater data for the front and back of the wall is entered Different levels and pressures can be used for assessment of the overall stability and Bending moment calculations The value of the unit weight of water is however a global value for all piezometers Groundwater can be entered in tabular form by selecting Groundwater
21. e view is fully expanded when the items have no symbol beside them Double clicking on an item will open the appropriate table view or dialog for data input 1 2 22 Preferences The Preferences dialog is accessible by choosing Tools Preferences from the program s menu It allows user to modify settings such as numeric format for output show welcome screen print parameters and company information These choices are stored in the computer s registry and are therefore associated with the program rather than the data file All data files will adopt the same choices Oasys Ltd 2014 3 Greta Oasys Geo Suite for Windows Preferences Numeric Format i j Company Info Engineering 5 significant figures Decimal 5 decimal places Page Setup Scientific E significant figures Smallest value distinguished from zero 1e 006 Restore Defaults V Save file every 10 Fs minutes Show welcome screen Numeric Format controls the output of numerical data in the Tabular Output The Tabular Output presents input data and results in a variety of numeric formats the format being selected to suit the data Engineering Decimal and Scientific formats are supported The numbers of significant figures or decimal places and the smallest value distinguished from zero may be set by the user Restore Defaults resets the Numeric Format specifications to program defaults A time interval may be set to save data files automati
22. ed Un 0 5 yB N s i 0 ON So CN s i 9 Bearing capacity factors N N 1 cot o N tan 45 q 2 e DI N N 1 tan 1 4 Shape factors s 1 0 2 N BYL s 1 0 1 N BYL Oasys Ltd 2014 Methods of Analysis S 1 0 1 N B L Since B lt lt L the above equations reduce to Load inclination factors 0 tan H V For 0 i 1 8 90 i 1 i 1 0 90 For o gt 0 i 1 90 i 1 0 4 if 0 lt o 0 if 0 gt 6 i 1 0 90 V net vertical force acting on 1m length of the wall H net horizontal force acting on 1m length of the wall Ground inclination factors I 9 94 1 Note The user can select the option to use ground inclination factors from Brinch Hansen 1970 In this case refer to ground inclination factor given above 2 1 5 Base Optimisation Greta provides a tool to optimise the base width by iterating the base width to achieve the minimum possible width giving full mobilization of soil strength the wall is checked for sliding overturning bearing and uplift using the factors of safety provided by the user The tool can be used to optimise the base width and also find the minimum toe or heel width required for heel or toe width specified respectively Oasys Ltd 2014 Greta Oasys Geo Suite for Windows To see how to use this tool please refer to Base optimisation tool 3 Input 3 1 Assembling Data It is best to make a s
23. ers can be entered by selecting Material Layers from the Data menu or the Gateway Beneath the base slab the same soil type must be selected for both sides of the wall Only one soil type is analysed for siding and reaction on the shear key Oasys Ltd 2014 GretaManual grw Material i EEN For each material layer the level of the base of the layer and the material type Must be entered The material type is selected from a drop down list of all the descriptions entered in the Material Properties module Upper soi ei Upper soil Am Soil behind 3 3 6 Foundation Properties The foundation properties used to assess the wall stability against sliding and for bearing capacity calculations should be entered here There are three data groups Soil structure interaction The friction and cohesion data used for calculating vertical shear at the front and back of the base are entered here This data is also used to calculate the resistance against sliding Bearing capacity data The user can choose to enter the cohesion and friction data from pre defined materials from the Materials table or define them separately The user has to specify drainage type and the method used in bearing capacity calculation The following methods are available 1 Brinch Hansen 1970 Drained analysis 2 EC7 Annex D D3 Undrained analysis 3 EC7 Annex D D4 Drained analysis 4 Meyerhof Drained analysis These are covered in
24. g capacity of the foundation soil is not checked by the program and must be carried out as a separate calculation by the user The location of the resultant force is also checked and reported If the rotation of the wall due to the applied force is towards the heel then the calculation is stopped The program also calculates the horizontal component of load on the wall and the sliding resistance of the foundation The user can specify separate shear strength parameters for the foundation soil to those used for creation of the active and passive pressures Application of factors to loads or soil strengths to assess the factor of safety of the wall is at the discretion of the user The Bending moment calculations option provides shear forces and bending moments in the stem and base of the wall This calculation also uses the full active and passive pressures on either side of the wall These are applied against the stem and base of the wall and not at the virtual boundaries These may be used in the structural design of the wall Oasys Ltd 2014 Greta Oasys Geo Suite for Windows Factor of Safety 1 A Failure 10 Foundation Properties 36 Friction 20 Active 7 11 46 Adhesion 20 G Air 34 Allowable Resistance 10 Gateway 2 Analysis and Data Checking 42 General 46 Analysis Options 33 General Program Description 1 Anchor 1 Graphical Output 2 44 Anchor Forces 7 Graphics Toolbar 2 Anchor Loading 39 Gravity Retaining Walls 1 Angle 36
25. he bending moments and shear forces in the wall for structural design calculations This analysis is optional e Uniform Surcharges These act vertically and may be included behind and in front of the wall For the Overall Stability Analysis surcharge loads are taken into consideration only in so far as they increase lateral earth pressures They is the option to exclude them from being used directly Oasys Ltd 2014 About Greta 6 i e excluding moment and forces generated by surcharge over footprint of wall in the equilibrium analysis e A line load acting at the centre of the top of the wall may also be specified Line load Line load Virtual Boundary Load Case 1 Load Case 2 Load case 1 is often critical for overall stability calculation Load case 2 is often critical for bearing pressure calculations and design for internal stability e Ground Anchors can be added down the stem of the wall Each anchor can have a different inclination elevation and anchor force The last four parameters above may be specified differently for each stage of the analysis 2 Methods of Analysis 2 1 General Greta performs two analyses to determine the overall stability of the wall and the bending moments in the wall The user may decide whether or not to carry out the latter The shear forces and bending moments calculated for the stem and toe and heel of the base can be used as the basis for structural design
26. ill not be reported Oasys Ltd 2014 Further the user may specify the method to be used for calculating soil pressures behind the wall as explained in Earth Pressures If the user is interested to compute the pressures behind wall arising due to compaction he needs to enter additional data such as effective line load per metre of roller critical depth for compaction pressures etc Details of these calculations may be found in CIRIA design guidance on modular retaining walls 3 3 4 Material Properties The properties for the different materials on either side of the wall are entered in tabular form For the data input select Material Properties from the Data menu or the Gateway Manual gw Material Properties parameters Above GWL GWL Eed mea mea TINA gt General A Overall Stability A Bending Moment Calculations Page General Cell 4 1 Brief descriptions for each of the material types can be entered here You need however to remain aware of the material number given to each of the material types This is located as a default value in the left hand column This number is used when assigning material types to either side of the wall thereby creating the Material Layers General parameters for each material are entered on the first page of the table Individual parameters for each of the methods of solution must then be entered The relevant tables are accessed by moving the mouse over the
27. in menu C Don t show this screen again This will open a new Titles window and allow you to proceed It is possible to open more than one data file at any one time The file name is therefore displayed in the title bar at the top of each child window d Manual grw Titles FE 3 2 1 Intranet link and emails To view the latest information regarding the Greta program or contact the support team click on i ES i the internet el or upport team buttons on the Start screen or select the options from the toolbar List of information required and actions before contacting support team Version of Greta see top bar of program or Help About Greta Spec of machine being used Type of operating system Please pre check all input data Access help file for information Check web site for current information Should you report a program malfunction then please attempt to repeat and record process prior to informing the team The web site aims to remain up to date with all data regarding the program and available versions Should any malfunctions persist then the work around or fix will be posted on the web site Oasys Ltd 2014 In addition if the user wants to email the input file that he she is currently working on to the support team he she can do so by clicking File Email button 3 3 Data Input Screens Data is input via the Data menu or the Gateway File Edit View Analysis Tools Window Help Units v Analysis O
28. ity Iteration 0 Base Opt Bearing Pa 97 69 2567 27 Sliding N 102 05 125 11 Overturning Nm 226 46 466 77 Uplift ON 216 69 LOandinn hama Thav abian N Dann Ant The tool dialog box is divided into three sections e Initial Geometry of wall that shall be edited only if the optimised results are accepted by the user e The optimisation and editing section where the user can specify different heel and toe width and optimise the other for the one he has specified e And the Comparison of results sheet Oasys Ltd 2014 3 3 11 Wall Geometry The geometry of the wall and wall weight must be defined here D Greta BearingCapacity grw Wall Geometry DAR Wall Stem Level at top j Thickness at top EN Wall Geometry Thicknesss at base Angle of back deg Wall Base Level of underside of base slab Thickness of base slab Distance from toe to front of wall stem Distance from heel to back of wall stem Shear Key Distance from toe to front of key Depth from underside of base slab Width Ground Level Level behind wall Ground inclination at the back of wall deg Ground inclination at the front of wall deg Average ground level across toe width Level in front of wall at the toe Sages All other dimensions in m Unit weight of wall 4 Output 4 1 Analysis and Data Checking Results can be obtained by selection of the Analysis menu File Edit View Data Tools Window Help Delete results Analyse
29. ketch of the problem before the computer is approached This should comprise a cross section of the proposed wall with the e ground surface level and inclination location of each soil strata e parameters of each material Overall stability and Bending moment calculations foundation material parameters phreatic surface location of any piezometers e magnitude of any loads location of any anchors 3 2 Opening the Program The following provides details of all the data required to run the Greta program On selection of the Greta program the main screen will open Oasys Ltd 2014 Input MM Greta 19 1 File View Tools Help DPM Ya aA 002 kd 4 n gt oN BK ime TaN Uk Oasys Checking security This is the main screen within which all data graphics and results are entered and viewed All further information appears in a series of smaller or child windows which are placed inside the main screen To start a new project file select e The Create a new data file option on the opening screen e File Newor the icon l i Oasys Ltd 2014 Greta Oasys Geo Suite for Windows Starting Greta File Click here to access latest IN O Create a new data file information on this program gt Open an existing file Click here to e mail the support team Program Status Version checking is disabled To view the version details select Help About from the program s ma
30. middle third and is towards the toe i e the eccentricit Oasys Ltd 2014 Methods of Analysis n Pmax Pmin Force under base compressive at all points Rotation towards toe eee ee B B Prin SIE B B Where B width of base e eccentricity of resultant R from center line of base lf the eccentricity is outside the middle third and towards the toe Pmax IL Pmin 0 Zero tension where force under base is not compressive 2V Pa ap Se 2 Oasys Ltd 2014 15 Greta Oasys Geo Suite for Windows Pain 0 bee 2 Where B width of base e eccentricity of resultant R from center line of base L Width of base in contact with ground i e having positive pressure If the rotation of the wall is towards the heel i e the eccentricity is negative then the calculation is stopped and a warning is provided because the active and passive pressures are not correct in this case The water pressure beneath the base is taken as linear profile between the water levels at the front and back of the wall This pressure profile is increased accordingly over the width of the shear key eg H Force due to water pressure under base and shear key 2 1 2 1 Shear key The forces in the shear key are determined from the summation of the horizontal pressures acting down the virtual front and back of the wall beneath the base and the total vertical and horizontal forces calculated for the as
31. nces The user is deemed to be conversant with standard engineering terms and codes of practice Itis the users responsibility to validate the program for the proposed design use and to select suitable input data Printed January 2014 Greta Oasys Geo Suite for Windows Table of Contents 1 About Greta 1 1 1 General Program Description c ceceeeeeeeeeeeee ener eeee ee RRE ne eeeeee sn eeseeeseeeeeeeseeeaeaeseeeeeeeeeeeseeeas 1 1 2 Components of the User Interface cccceececeeeeeeeeeeeee ee eeeeee ee eeeeee se eeeeeeseeeaeeeseeeaeeeseeeseeeseeeseees 2 1 2 1 Working with the Gate UU 2 122 EN ET ET TEE 2 Ta Program FERIE S enee EEN ENEE de 4 2 Methods of Analysis 6 KN Wb e CT EE 6 2 1 1 Overall Stability ssssssssssssssesssssscsesssecsssesssseseaesesseseaesssesseaesesesseacsenseneaeseseeneaesesssaeacsesssausestsseanseeessaeaesesanasseessneats 7 2 1 1 1 Plastic stress bloe ege age angen Gti een oats Paden atoll espa ne ieee eee 10 2122 SIIGING CHECK EE 10 21 134 Bearing CheCkis tiierviien he ei eel dee Eege EA Edel geen r due 11 2 1 2 Bending Moment Calculations EE 11 2 1 2 1 leet EN arr rar rense ea a N ES a eler penn ee 15 2 1 2 2 Bending moments and Shear forces 16 2 1 2 3 COMPACTION PFESSUIES ege EES ER ES REE Nea aa EEN ra 17 2 1 3 Earth Pressures ose GEES as eee EE 19 2 1 3 1 Friction and eiert eelere 20 2 1 4 Bearing Capacity ssssssssssssscsssssssesssesssssssssssssesns
32. ns The fields should therefore be used to provide as many details as possible to identify the individual calculation runs An additional field for notes has also been included to allow the entry of a detailed description of Oasys Ltd 2014 Input 32 the calculation This can be reproduced at the start of the data output by selection of notes using File Print Selection 3 3 1 1 Titles window Bitmaps The box to the left of the Titles window can be used to display a picture beside the file titles To add a picture place an image on to the clipboard This must be in a RGB Red Green Blue Bitmap format Select the Paste button to place the image in the box The image is purely for use as a prompt on the screen and can not be copied into the output data Note Care should be taken not to copy large bitmaps which can dramatically increase the size of the file To remove a bitmap select the Remove button 3 3 2 Units The Units dialog is accessible via the Gateway or by choosing Data Units from the program s menu It allows the user to specify the units for entering the data and reporting the results of the calculations These choices are stored in and therefore associated with the data file Quantity Conversion factor Displacement 1000 per m Force LN L 0 001 per N Length level 1 per m Stress 0 001 per Pa Reset Units Default options are the Syst me Internationale SI units KN and m The
33. ode EN1997 1 2004 the amount of shear stress which can be mobilized at the wall ground interface should be determined by the wall ground interface parameter 6 e concrete wall or steel sheet pile wall supporting sand or gravel may be assumed to have a design wall ground interface parameter 5 kpwhere k should not exceed 2 3 for precast concrete or steel sheet piling e For concrete cast against soil a value of k 1 0 may be assumed e For a steel sheet pile in clay under undrained conditions immediately after driving no adhesive or frictional resistance should be assumed Increases in these values may take place over a period of time e For walls where the virtual back is unrestrained fill to fill the interface angle of wall friction amp should be considered to be zero CIRIA C516 Overall Stability For the virtual back and front and ends of the wall base the tangential stresses are taken as boundary friction active p a Land boundary friction active D tan A boundary adhesion ch Where specified boundary friction for overall stability Cy Specified boundary cohesion for overall stability Bending moment calculations Where the wall stem remains vertical the friction calculation at the wall interface stem and base is the same as for overall stability but uses the friction parameters given for calculation of the Bending moment calculations Where the wall stem is inclined the calculations for the friction fo
34. oil Stress 10 Virtual 46 Virtual Back 7 Virtual Front 7 W Wall Base 33 39 Wall Base Forces 1 20 46 Wall And Base Forces 11 Wall Geometry 42 Wall Stability 36 Water Pressure 7 11 Weight 7 Greta Oasys Geo Suite for Windows Endnotes 2 after index Oasys Ltd 2014
35. ormat 5 List of References 5 1 References CIRIA Publication C516 2000 Modular Gravity Retaining Walls Design Guidance Oasys Ltd 2014 Manual Example 6 Manual Example 6 1 General The data input and results for the Greta manual example are available in the Samples sub folder of the program installation folder The example has been created to show the data input for all aspects of the program and does not seek to provide any indication of engineering advice Screen captures from this example have also been used throughout this document This example can be used by new users to practice data entry and get used to the details of the program 7 Brief Technical Description 7 1 Greta Greta is used for analyzing gravity retaining walls It performs two calculations which assess the overall stability of the wall and the forces in the stem and base The Overall stability option is used for examining the static equilibrium of the wall The program assumes that full active and passive soil pressures develop on the virtual boundaries behind and in front of the wall respectively The wall is assumed to act as a rigid body together with any soil encompassed by the vertical planes through the extremities of the base The total horizontal and vertical forces are resolved to calculate the force on the base of the wall The required reaction of the foundation soil is then calculated to provide equilibrium of the wall The bearin
36. p left corner of the page If Border is selected this gives a border but no header information If Clipped is selected the output is clipped leaving a space for the logo This has no effect on text output 1 3 Program Features The main features of Greta are summarised below e Structural Types A number of different wall shapes may be specified with tapering and or sloping stem and optional base toe heel and key Oasys Ltd 2014 Greta Oasys Geo Suite for Windows Mass Gravity T Wall with Shear Key Cantilever wall with Cantilever wall with heel Toe and shear key Note The wall is assumed to be rigid and can only be made of one material type with a single specified unit weight Soil Strata The program allows a number of different soil strata to be specified behind and in front of the wall The ground surface behind the wall may be specified as sloping The surface in front must be horizontal Soil Coefficients Different soil coefficients may be specified for the calculation of Bending moment calculations and Overall Stability Ground Water Pressures The groundwater pressure distribution may be defined as a hydrostatic or piezometric Load Cases There are two load cases in the program Overall Stability This is used for assessing the overall stability of wall especially with regards to overturning sliding and bearing failures Bending Moment Calculations This is used for evaluating t
37. ptions Titles v Wall Geometry v Material Properties v Material Layers v Foundation Properties v Groundwater v Surcharges v Anchor Loading The information can be entered in any order but Material Properties should be entered before specifying Material Layers Once the data has been entered the program places a tick against that item in the menu list The following describes each of the menu items in detail Oasys Ltd 2014 Greta Oasys Geo Suite for Windows 3 3 1 Titles The first window to appear for entry of data into Greta is the Titles window d GretaManual grw Titles Job Number Initials Last Edit Date Bitmap has wl ap Ma7 Job Title Oasys Example Subtitle Including wall base force Calc Heading Calculations Written by Greta version 18 2 Notes Greta example file This window allows entry of identification data for each program file The following fields are available Job Number allows entry of an identifying job number Initials for entry of the users initials Date this field is set by the program at the date the file is saved Job Title allows a single line for entry of the job title Subtitle allows a single line of additional job or calculation information Calculation Heading allows a single line for the main calculation heading The titles are reproduced in the title block at the head of all printed information for the calculatio
38. rces are separated into their horizontal and vertical components where Friction Oasys Ltd 2014 21 Greta Oasys Geo Suite for Windows horizontal friction active p tany tang vertical friction active D tang horizontal friction passive D tan y tang vertical friction active D tang Where y angle of the wall stem to the vertical front and back specified friction for Bending moment calculations Adhesion horizontal cohesion active p tany CG vertical cohesion active D CG Use D for passive equations c Specified wall adhesion for Bending moment calculations For information on friction beneath the base of the wall see Sliding check 2 1 4 Bearing Capacity Terzaghi s equation Vit cN si g ON So 0 5 yB N s i 9 c CG CIF Un Ultimate bearing capacity of soil c Cohesion between soil ground and wall q Effective stress in front of wall g Unit weight of soil above the base level B Effective width of wall base f Angle of internal friction No Ny N Dimensionless bearing capacity factors Sy Sy Sy Shape factors ke iy i Load inclination factors or Iy Dy Ground inclination factors Calculation of effective stress q Effective stress is the cumulative sum of weight of soil in front side of the wall minus water pressure under base Effective width of wall B The entire load acting from above is combined into two component forces having V as the vertical
39. sessment of the forces in the stem and base The following table defines the reported calculations Net force on key Fa Pix Pack Resultant horizontal force R Bending moment calculations Allowable shear on base D R U tand GA Bending moment calculations Additional force on shear key Fig R if R gt else F 0 Oasys Ltd 2014 Methods of Analysis e Assumed lever arm of L 2 3 depth of the key h additional force Total horizontal force on key Risk Pix Pic EA Met I k P KI 1 Fsg h 12 Lever of action of total force Ly h p ps as asi S 2 Risk Bending moment in key DM Bt lsk wi a l I I I p I I h I Pask I I l l l oat t n Virtual front Virtual back beneath base beneath base Note The above assumes that the shear key is capable of providing the horizontal force required to give horizontal equilibrium The user needs to check that the soil in front of the key is capable of sustaining this force 2 1 2 2 Bending moments and shear forces The bending moments and shear forces are calculated at specified sections down the wall and along the toe and heel of the base I 4 increments down stem 5 increments at heel 2 increments at toe The location of the shear key is checked and the spacing of the increments adjusted to place a point at either side of the key as shown The shear forces are calculated from the summa
40. ssive pressures Oasys Ltd 2014 Methods of Analysis 1 Net horizontal force is towards heel 2 1 1 1 Plastic stress block The plastic stress block is defined as the area of plastic deformation beneath the wall The total horizontal and vertical forces calculated for overall stability are resolved to provide an overall resultant force The intersection of the resultant with the base of the wall is used to locate the centre of the plastic stress block The total width of the stress block is defined as twice the distance of the intersection of the resultant force from the toe of the wall at A The vertical soil stress within the block is taken as R 2x and horizontal soil stress as R 2x 2 1 1 2 Sliding check A check is made on the sliding resistance of the wall using the restoring and disturbing components of horizontal force calculated for overall stability The allowable resistance R is taken from the input foundation properties where Oasys Ltd 2014 d Greta Oasys Geo Suite for Windows R R Tand c A R Resultant vertical force Overall stability 5 Soil Base friction angle Cy Cohesion under base A Area of base or stress block length per unit width 2 1 1 3 Bearing check The program also checks whether the vertical stress within the stress block is less than the bearing capacity of the foundation However this check is not carried out when the shear key is present In this
41. ssssneacsesseaeaessesessseseeseauaesesseasaeessaeaesesesssaeasessaeaesesteneassesseaeatanenss 21 2 1 5 Base Optimisation sscsssssscscssssssssessesseessssssesessssessseacsssseaesesssssaesesseseaeaesesseasaesssaeanseseessaeaeessanaesesteneasseeseaeaesanes 26 3 Input 27 31 Assembling Dala serieren oeer En EEG coccate ot tdecsa Eege ees 27 3 2 Opening the d dee LC RE 27 22 Intranetlink ANd ei AllS EE S EAE E A ERREECHEN NEES 29 3 3 Dala Input Screens se ccc scene eege Neger eege eege eege eech 30 GE e Wu 1 TEE 31 3 3 1 Titles Window Bit MAPS EE 32 KE SR TC 32 G KRIEIDO Oe IT 33 3 3 4 Material Properties een 34 3 3 5 Material UE 35 3 3 6 Foundation Properties scscscseseseseseteseseteneeteneneneaeeneneseseeaeaeseaeaeaeaeseaeasaeaeaeaeaeaeaeasaeaeaeaeaeaeaeaeaeaeaeaeaeaeanaeaeaes 36 BLARE aT o K U D E EE AE EE O RC PN aD O E AE Bel Soe AE 37 EEN DTN 38 3 3 9 Anchor Loading 1204 39 3 3 10Base Optimisation Tool eessen 40 3 3 11Wall Ge OM DE VE 42 4 Output 42 4 1 Analysis and Data Checking cccceececeeeeeeeeeeeee ee eeeeee eee eee mennan nnmnnn 42 KS KC EI ei e LEE 43 Oasys Ltd 2014 Contents l 4 3 Graphical Output oo El I Eg 5 List of References Bil References us E ears heks 6 Manual Example G21 General eongisnesdeitizeen deg geesde eege es 7 Brief Technical Description TA e CC WE Index Oasys Ltd 2014 1 Greta Oasys Geo Suite for Windows 1 About Greta 1 1 General
42. ting on the wall A effective area of the foundation effective width length with H lt A c Ground inclination factors g 1 Note The user can select the option to use ground inclination factors from Brinch Hansen 1970 In this case refer to ground inclination factor given above q Total surcharge at the bottom level of base EC7 Annex D D4 Drained analysis In this method only drained conditions are considered Ui eN sig 0 5 yB N s i 0 A N Saiga Bearing capacity factors N r 2 5 14 c N tan 45 4 2 er 9 4 N 2 N 1 tan amp for rough base Shape factors S 1 BYL sin Bun 1 0 3 BIL S s N IMN 1 Since B lt lt L the above equations reduce to Spe Spe sy Oasys Ltd 2014 25 Greta Oasys Geo Suite for Windows Load inclination factors I i 1 iN tan a i 1 H V A c cot NON 1 H V A c cot i Where m 2 BYL 1 BYL Since B lt lt L m 2 V net vertical force acting on 1m length of the wall H net horizontal force acting on 1m length of the wall A effective area of the foundation effective width length Ground inclination factors I 9 94 1 Note The user can select the option to use ground inclination factors from Brinch Hansen 1970 In this case refer to ground inclination factor given above Meyerhof Drained analysis In this method only drained conditions are consider
43. tion for the development of Bending moment calculations provides shear forces and bending moments in the stem and base of the wall The calculation also uses the full active and passive pressures on either side of the wall These are applied against the stem and base of the wall and not at the virtual boundaries In addition to active pressures behind wall the user can also specify KO pressures and compaction pressures These may be used in the structural design of the wall Note Separate soil parameters and anchor loads can be applied to each type of analysis Oasys Ltd 2014 About Greta 2 1 2 Components of the User Interface The principal components of Greta s user interface are the Gateway Table Views Graphical Output Tabular Output toolbars menus and input dialogs Some of these are illustrated below File Edit View Data Tools Window Help de IERCH Ko Tet 1 thd Oasys gg o DIS d GretaMan grw Foundation Properties E cl Standard toolbar wl Greta toolbar espa Graphics toolbar z smeo L rb erz Model Image Titles view Soll Structure interaction Foundation Properties dialog Allowable Sol Base Fiction deg 37 Allowable Soi Base Cohesion kN m2 0 Unts Analysis Options Wal Geomety Job Tile Meee fpa 9 OASYS VALIDATION TESTING as Beating Capacity of foundation 7 Cany out bearing capacity calculations Material m D Subtite Smith eg7 2 cant wall doped gmd amp back Cake Heading
44. tion of the vertical and horizontal forces acting on the stem and base as follows Oasys Ltd 2014 Greta Oasys Geo Suite for Windows Horizontal forces on stem e Soil pressures e Water pressures Vertical forces on base Downward e Friction at heel on base Weight of soil on toe or heel Weight of base slab Surcharges Weight of shear key Upward e Friction at toe on base e Soil pressure beneath base e Water pressure beneath base Any horizontal forces on the stem due to friction are not included The bending moments are calculated by taking a lever arm from the top of the stem and the toe and heel ends of the base slab respectively The moment due to any horizontal force on the shear key is also included in the calculation for the bending moments in the base 2 1 2 3 Compaction pressures Based on CIRIA C516 the compaction pressures need not be used for overall stability calculation where forward movement of the retaining wall is possible i e it is not propped by a structure in front of it and acceptable the deflection would not exceed a serviceability limit state The method used for the calculation of compaction pressures was originally proposed by Ingold 1979 but has been stated more recently by Symons and Clayton 1992 The pressures calculated are most relevant for the internal design of retaining walls with reinforced concrete stems The stem deflection is often too small for these locked in pressures to be relieved b
45. y its forward deflection Oasys Ltd 2014 Methods of Analysis 18 Rigid wall Shrm Oh It is reported that pressures greater than those calculated from Ko o to a depth they called ho defined as n PP K ay Where K is coefficient of earth pressure at rest P is the effective line load per meter of the roller and y is the density of the material undergoing compaction DM The maximum pressure o hrm can be calculated from 2Py Thm Pe and this occurs below a depth z where Oasys Ltd 2014 19 Greta Oasys Geo Suite for Windows 2P Vo 2 1 3 Earth Pressures The active and passive earth pressures are calculated at the top and base level of each stratum and at intermediate levels where there is a change in linear profile of pressure with depth e g location of phreatic surface The active and passive coefficients should take account of the inclination of the wall to the vertical the sloping ground in front and behind the retaining wall if any the wall roughness the selected design approach the limit state being considered etc Intermediate levels are also placed at the top and underside of the base and bottom of the shear key The effective active and passive pressures normal to the wall are denoted by p and D respectively These are calculated from the following equations P a ka Cy i Kac c P kp 6 kpg Where c effective cohesion or undrained strength as appropriate o
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