Recommendations for Design and Analysis of Earth Structures using Geosynthetic Reinforcements - EBGEO

Transl ation of the

2nd German Edition

Publ ished by

the German Geotechnical Society

(Deutsche Gesellschaft fUr Geotechnik e. V., DGGT)

DGGTU Deutsche Gesells.:haft fiir Geotechnlk e. V. German Geotechnical Society

Contents

Preface to the English edition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VJII

Notes t'or the User . . .... .. . . .. . . .. . .. . . .. . .. . ... .. .. . . . .. . .. . .. ... XXi

l. l 1.2

1.2.1 1.2.2 1.2.3 1.2.4 1.3 1.4

2

2.1 2 .1.! 2. 1.2 2. 1.2. I 2.1.2.1.1 2.1.2. 1.2 2.1.2.2 2.1.2.3 2.I .3 2.2 2.2.I 2.2.2 2.2.3 2.2.4 2.2.4.1 2.2.4.2 2.2.4.3 2.2.4.4 2 .2.4.4.1 2.2.4.4.2 2.2.4.4.3 2.2.4.4.4 2.2.4.5 2.2.4.5.1

lntroduction to the Recommendations and their Application Principles ....... . .... .. . .. ... . ..... . . .

National and Tnternational Regulations ... . .. . . .. . . .... . . . .. . . . . Types ofAnalysis and Limit Stat:es using the Partial Safety Factor Approach . . ....... . .. . ....... ... 2 New Standards Generati011 and Transitional Regulations . . . . .. . . . 2 Effects and Resistances ................................ . ..... 3 Limit States . .. . . ..... . . .. .... . .. . .. . ...... .. ...... . : . . . . . .. 3 Applying EBGEO in Conjunction with DIN EN 1997-1. ... . . . . . . 5 Examples ofReinforced Earth Structures . .. . . . .. . .... .. . . .. . .. . 7 Generai Definitions .............. . .. . .. . . . . .. ....... . . .. .... 8

Demands on Materials . .. .. ...... . .. . .... . .......... . . ... ... 9

Soi l ....................................................... 9 Ground lnvestigation ... .. ......... . ......................... 9 Fili Soil ....................... . ............... . ............ 9 Soil Mechanics Demands . . .. . ....... . .. . . .. ...... .. ....... . . 9 Predominantly Statically Loaded Stmctures .... . .... .. . . ....... 9 Predominantly Dynamically Loaded Structures ................ l O Soil Chemistry Demands ... .. .... .. ........... .. ..... ..... .. 10 Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l O Back-fill and Cover-fill Soils .... ... .. ...... ..... ...... ..... . I O Geosynthetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Generai Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l I Raw Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Product Properties and Demands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l l Testing and Reduction Factors ........... ..... . ...... . ....... 12 Generai Recommendations ............. .. .......... . ........ I 2 Product Tdentification (DTN EN TSO I 0320) . . .. ...... . . . . .... . l 3 Mass Per Unit Area (DIN EN ISO 9864) . .. . . . .. . .. . . .. . . ..... I 3 Short-term Load-Extenson Behaviour ... .. . ........... .. ..... . l 3 Tensile Strength and Straù1 (DIN EN ISO 10319) ...... . ....... 13 Axial Stiffness . .. . . ..... . .. . . . ..... . ...... .. . . .. . . .. . . ..... 17 Uniaxial and Biaxial Reinforcement .. . . .. . . .. . . .. . . . .. . .. .... l 8 Serviceability Limit State/Strain Behaviour. . . . . . . . . . . . . . . . . . . . 18 Long-term Load-Extension Behaviour (Creep Rupture, Creep) ... 18 Generai Recommendations .. . .. . . .. . . .. . . .. . . .. . .... . .. . .... 18

Reconummdationsfor Design tmd Atu1lysis uf Ear1h Srructures using Geosymheric Reinforcemenrs (EBGEO). Gennan Geotechnical Society. © 20 11 Emst & Sohn GmbH & Co. KG.

lX

Published by Emst & Sohn GmbH & Co. KG.

2.2.4.5.2 2.2.4.5.3 2.2.4.5.4

2.2.4.6 2.2.4.6.1 2.2.4.6.2

2.2.4.6.3 2.2.4.6.4 2.2.4.7 2.2.4.7.1 2.2.4.7.2

Determining Reduction Factor A 1 from Creep Testing . . . . . .. .. . 19 Reduction Factor A 1 for Crecp Failurc Behaviour . .. ... . . . ..... 20 ldentifying Long-term Struin Behaviour by Evaluating lsochrones .. . .. . . .. . . .. . ..... .. . . .. .. .. . .. . .. 21 Rcsistance to Mechanical Damage During Jnstallation .... . . .... 24 Generai Recommendations . . .. . . . .. . .. . . . .. . .. ...... ... . .. . . 24 Reduction Factor A2 for Damage to Geosynthetics During Transportation, lnstallation and Compaction ................... 24 ln-situ Testing . .. ... . . . ... . .. . . .. . . . .. .... .... . . . . . . ....... 25 Laboratory Testing (DTN EN ISO l 0722) . . ... . ... • ....... .. . . 26 Joins and Connections .......................... . . ......... . 26 Generai Recommendations .. . .. .... .. . .. . .... . . ..... . .. ..... 26 Reduction Factor A3 for J unctions, Joins, Seams and Connections to Other Structural Elements .. . ..... .. . .. ... . ... . 26

2.2.4.7.3 Detennining the Reduction Factor A3 by Testing . .. . . ... . ...... 26 2.2.4.8 Chemical Resistance ... . . . .... .. . .. ..... . . ................. 27 2.2.4.8.1 Reduction Factor A4 for Enviromnental Chemicallmpacts ..... . 27 2.2.4.8.2 Determining Chemical Resistance by Testing .. . .. ...... . . .. . . . 27 2.2.4.9 Additional Environmental Impacts . . .. . . .. . .. . .... . . . . . ...... 28 2.2.4.9. 1 Microbiological Resistan-ce .. . ..... . ...... . .. . . ....... . . .. . .. 28 2 .2.4.9.2 Biologica! Resistance and Vandalism .. .... .. . .. .... . . .. .. . . .. 28 2 .2.4.9.3 Weathering Resistance (UV Resistance) .. . .. . . ..... .. ... . .. . . . 28 2.2.4.10 Effects ofPredominantly Dynamic Actions .... .... .. . .... ... . . 29 2 .2.4.1 0.1 Reduction Factor A5 for Predominantly Dynamic Actions ..... . . 29 2.2.4.1 0.2 Determining the Reduction Factor A5 for Predominantly

Dynamic Actions by Testing . . ..... . . . .. . .. ... .. . . . . .... . .... 29 2.2.4.11 Friction and Composite Behaviour . .. . .. . . .. ................. 29 2.2.4.11.1 Generai Recommendations .. . . . . ...... ..... .. . .. . . .. . .. . .... 29 2.2.4.1 1.2 Determining Composite Coeftìcients by Testing . ... . .. . .. .. ... 31 2.3 Bibliograpby .. . . ....... .. .. . .. . . . .. . ........ . ... .. .. . .. . .. 32

3

3.1 3.2

3.3 3.3.1 3.3.2 3.3.3 3.3.3.1 3.3.3.2 3.3.3.3 3.3.4 3.4

x

Analysis Principles ............. . . . . .... . .................. 3 5

Generai Principles . . .. . .. . .... . . ..... . . . . .. . ... . .. . . .. . .. . .. 35 Allocation of Geosynthetic-reinforced Structures to Geotechnical Categories . .. . . .............. .' .............. 37 Design Resistances . .. . . .. . . .. . . .. . . .. . .... . . . . . .......... . . 38 Structural Resistance of Geosynthetics ..... .. . .. . . .. . . .... .. . . 38 Determining Reduction Factors . . .. . . .. . . . .. . . . ......... .... . 39 Pull-out Resistance ofGeosynthetics . . .. . . . ........... .. . . ... 39 Characteristic Pull-out Resistance of Geosynthetics .... .... . ... 39 GEO Pull-out Resistance Design Values ........ .. . . . .. . .. . ... 39 STR Pu!J-out Resistance Design Value .... . . . .. . .... . ......... 40 Axial Stiffness of Geosynthetics in the Serviceability Limit State 40 Partial Safety Factors - Supplementary Regulations to DIN l 054 40

~

4.[ 4.2 4.2. 1 4.2.2 4.2.2. 1 4.2.2.2 4.2.2.3

4.2.2.4 4.2.3 4.2.4 4.2.4.1

4.2.4.2

4.2.4.3 4.2.4.4 4.2.4.5

4.3 4.4 4.5 4.6 4.7 4.7.1 4.7.1.1 4.7.1.2 4.7.2 4.7.2.1 4.7.2.2 4.7.3

4.7.3.1 4.7.3 .2 4.7.3.3 4.7.4 4.7.5 4.7.6 4.7.6.1 4.7.6.2

Embankments on Soft Soils . ... . . ......... . .. . . . . .. . .. . ... . 43

<.ìeneral Recommendations .. .. . .. . .. ... . . . . .. . . .. . . . . ...... . 43 Analysing Global Failure . .. .. . .. . . .. . ..... . .. . .......... . .. 44 Generai Recommendations . ... . .. . ....... .. . .. . .. . .......... 44 Failure Mechanisms .. .. . ... . .............. . .. . ........ . .. . . 45 Failure on Circular Slip Planes . . ...... . .... .. . . . .. .... . . . .... 45 Detìned Slip Piane in Soft Soil. . .. . . ... . .. ... .. .. ............ 45 Slip Piane Between Geosynthetics and Fili Soil or Between Geosynthetics and Soft Soil. .... . .. . . . .. . . .. . ..... 45 Adoptìng Reinforcement Wrap-around .... ... ................. 45 Actions ... . . . .. . .... . .. . ......... . .. .. .. .................. 49 Resistances ......... .. . .. .. . ...... .. ... . .......... . ........ 49 Design Yalue ofthe Friction Resistance o n Top of the Geosynthetics Ro,d .. .. ............. . . . . ... . ... 49 Design Value of the Shear Resistance on the Botto m of the Geosynthetics Ru d ...... ..... . .......... 49 Design Value of the Pull-out Resìstancè R,\,d ......... .. ... ... . 50 Design Resistance ofthe Geosynthetic Reinforcement Ra,d .... . 50 Design Value of the Friction Resistance on Top ofthe Geosynthetic R3 d ....... ... ..... . .. . . . . . . . ..... 50 Analysing the Stability ofthe Ground against 'Squeezing Out' ... 51 Analysing Bearing Capacity .... ... .... .. . . . .. . . .. ...... . .. .. 52 Engineering Notes ........... . .. . . .. . . .. .... ..... . ......... 53 Bibliography . . .. . . . .. . .. . ..... . . .......................... 53 Example Embankment on Soft SoiL . . .............. ... . . . .. .. 53 Failure on Circular Slip Planes ..... ..... .. .... . . .. .... . . .. .. . 54 Initial Stability ............ .. . . . . . . .. .... . . .... . .. ...... . . . . 55 Fina! Stability .. .. .... . .. ................ . ................. 56 Detined Slip Piane in Soft Soil. .......... .. ................. . 57 lnitial Stability ............................ ...... .. . .. ...... 57 Fina! Stability ......... . .. . .. . . .. . . . .. . .... . .......... . .... 60 Sii p Piane Between Geosynthetics and Fili Soil or Between Geosynthetics and Soft So i l taking the Re-inforcement Wrap-around into Consideration ...... 60 Generai Recommendations ......... . . .. . ....... ............. 60 Initial Stability . . . .. . . .. . . .. . .. . .... . . .. ... ................. 60 Fina! Stability .. . ....... .... .. ............. ... ............ . 62 Analysing the Stability ofthe Ground against 'Squeezing Out' .. . 63 Analysing Bearing Capacity .............. . . .. . .............. 64 Selecting the Geosynthetics .. . ................... . ... .. ..... 64 Analysing Reinforcement Failure ...... ..... .. ... ............ 64 Analysing Reinforcement Pull-out . ............. .... .. . . ..... 66

XI

5

5.1 5.2 5.3 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.4 5.5 5.5.1 5.5.2 5.6 5.6.1 5.6.1.1 5.6.1 .2 5.6.1 .3 5.6.1.4 5.6.1.5 5.6.2 5.7 5.8 5.9

5.9.1 5.9.2 5.9.2.1 5.9.2.2 5.9.2.3 5.9.2.4 5.9.3 5.9.4

6

6.1 6.2

6.2.1 6.2.2 6.3 6.4 6.5

xn

Reinforced fo undation Pads . .. . .. . . .. . . .. . . . . . . . . ... . . .. .. 71

Detinitions . . . .. ........... ..... . . . .... .... . .. . .. .... . ..... 7 1 Application and Modus Operandi .... . .............. . .... . ... 7 l Design and Engineering Notes .. . . .. . .... . ...... . .... .. ...... 7 1 Construction Principle .. .. . .. .. ...... . . . . ...... . . ..... . . .. . . 71 Reinforcement Conftguration . . ... . ... .. .. . .. . ....... .... .. . . 72 Reinforcement Lengths .... . .. . . .......... . . .. . . .. . .. . .. .. . . 72 Foundation Pad Dimensions ... . . . .. . .. . . . . .. . .. . ......... . .. 72 Building Materials ........... . . . . . . .. ...... . . . . .. . ......... 73 Actions and Resistances . . ...... .. .. ... .. . . . . .. . .. . . ..... .. . 73 Analysing the Reinforc-ed foundation Pad .... . ..... . .. . .. . .... 73 Generai Recommendations . .... .. . ........ .. . . . . .. . . . . .... .. 73 Etfecrs . .. ....... . .. . ...... . .. . .. . . . ....... .. . . .. . ......... 73 Analysis and Design ........ . .... . ... . .. . ... . . . . . . . . . . .. . ... 74 Analysing Bearing Capacity ........... . .... ... . . .. . .. . .. . . .. 74 Analysing Sliding Safety (STR) . ... ..... ... ....... . . .. . .. . ... 74 Analysing Bearing Capacity (STR) .. . ... .. . . .... .. . . .. . ..... . 74 Analysing Global Stability (GEO) . ....... . . ....... ..... ... .. . 79 Analysing Reinforcement Failure (STR) ........ . ..... . . ...... 79 Analysing Reinforcement Pull-out Resistance (STR) . .. . . ...... 79 Serviceability Limi t State Analysis .... . . .. . . .. . .. . . .. . . .. . .. . 80 Notes on Execution .................. .. .................. . .. 8 1 Bibliography . .. . ....... .. .... . .... ... ......... . .... .... ... 81 Example of a Reinforced Foundation P ad below a Strip Foundation .................................... 81 Geometry, Loads and Soil Mechanics Parameters .... . ... . ..... 81 Analysing Bearing Capacity ..................... . .......... . 83 Design without Foundation Pad . . .. . . .. . . . .. . . .. .... . . .. . . .. . 83 Design with Foundation P ad- Foundation Pad Geometry ....... 85 Analysing Bearing Capadty of the Unreinforced Foundation Pad 86 Design with Reinforced Foundation Pad ........... .... .. . .. .. 87 Analysing Sliding Stability . . .. . . . .. . .... . .. . . . ..... . .... . ... 89 Serviceability Limi t State Analysis .... .. . . ............... . .. . 89

Transport Routes ............... . ... .. .... .... .. . . .. . .... . 91

Generai Recommendations . . . ... . . . .... . . .. .. .. ...... ..... .. 91 Trafficked Areas with Non-stabilised Pavement and Large Allowable Deformations . . . .. . . .. .... .. ... . .. .. . . . . 92 Applications . . . .... .... .. .... . .... ... .... . . ............. . .. 92 Design Concept ............................. ......... ... .. . 92 Trafficked Areas in Railways Engineering . .. .... . . .. . . .. . . .. . . 94 Installation and Emplacement Notes . . .. . . .. .... . . .. . . .. . . .. . . 95 Bibliography ................ . ....... .. . . . .. . .... . . . ..... . . 95

7

7.1 7.2 7.2.1 7.2 .2 ~ ")

l .. )

7.3.1 7.3.2 7.3.3 7.4 7.4.1 7.4.2 7.4.3 7.4.4 7.4.5 7.4.6 7.4.7 7.4.8 7.5 7.5.1 7.5 .2 7.5 .3 7.5.4 7.5 .5 7.5.6 7.5.7 7.5.8 7.5.9 7.6 7.7 7.8 7 .8.1 7.8.2 7.8.3 7.8.3.1 7.8.3.2 7.8.3.3 7.8.3.4 7.8.2.5 7.8.4 7.8.4.1 7.8.4.2 7.8.4.3

Rctaining Structurcs . . . . . .. . . ... . .. . ......... . .. . .. . . . . . .. 97

Detìnitions . . . .. . . . .. . . . . . . . . . . . . . .. . . ... . .. . . . . .... . ...... 97 Design Notes ..... . ..... . ............. . .. . .... . .. . . . . . ..... 98 Demands and Boundary Conditions . . .. . .... ... . . .. . . . . . : . ... 98 Ge01netry .. . ..... . .... . .. . .. . . .... ........ . .. . .. .......... 98 Analysis Principles . ... . ....... . .. . .. . .... .. . .. . ...... . ..... 98 Generai Principles .. .. .. . ... . .. . ........... . ..... .. . .... .. .. 98 Sii p Planes and failure Mechanisms . . .. .... . . ........... . .... 99 Analysis Overview . . . . .. .............. .. ... . ... . ...... . ... l 00 Analyses in the Ultimate Limi t State (ULS) . .. . ........ . . . . . . l 03 Generai Recommendations ......... . .. . . .. . . . . . . . ......... . l 03 Actions an d Effects .. . .. . ... . ............ ... .... ........... l 04 Resistances . . ........... . .. .. . .. .. .. .. .. ... .. ... .. ........ l 04 Analysing Generai Failure/Siope Failure (GEO) ... . . . .. . ..... l 05 Analysing Bearing Capacity (STR) .. . . . . .. . . .. . ... . . .. ...... l 05 Analysing Sliding Safety (STR) ...... . . .. . . ......... .. . .. .... 105 Position of Bearing Pressure Resultant . .. . ... .. . ... .. . ........ l 06 Special Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l 07 Serviceabil ity Limit State (SLS) Analyses . ..... . ....... . .. ... l 07 Genera! Recommendations ........... ...... .. . . ..... ....... l 07 Analysing the Position of the Bearing Pressure Resultant. .. . ... l 09 Displacements in the Base Piane .. . .... . ....... . . .. . ........ l 09 Ground Settlement v v .... ..... ......... . ...... . ... ...... . . l 09 1ntrinsic Settlement o.fFill Soil vE ........... . .. . .. . ...... ... 110 Horizontal Displacements ofthe Slope Front vHi ......... . . ... 11 O Shear Deformation in the Retaining Structure vs .......... . .. . 112 Vertical Disp1acements at the Surface v0 . .... ...... . ..... . .. . 112 Numerica! Methods . .................. . .. .... . . ....... . ... 112 Facing Analyses ........... .. . . .. . . ............ ........... I 12 Bibliography . . .... . .. . .................. . . . ........ . .... . 116 Retaining Structure Design Ex.ample ...... .. . . .. . .... . .. . . .. 118 Geometry, Soil Properties and Load Assumptions . ... ......... 118 Detennining the Charactelistic Actions ....... . .............. 119 Analysis in the Ultimate Limit State (ULS) ........ . .......... 119 Analysing Sliding Safety .................. . ......... . ... ... 119 Position ofBearing Pressure Resultant. .... .. . . .. . . . .. .. .. .. . 121 Analysing Bearing Capacity . . .. . .. . . . .. . ................... 122 Analysing Generai Failure ................... .. .. .... ....... 123 Analysing Facing for Partially Deformable Facing Elements .... 129 Serviceability Limit State (SLS) Analysis ..... .... . . .. . ...... 129 Analysing the Position ofthe Bearing Pressure Resultant. ...... 130 Displacements in the Base Piane ......... . .... .. .. . ......... 130 Settlements . . .... . .. ..... .. . ............. . .. .. .. . .. . . ..... 130

XIII

8 Landfìll Engineering -Rcinforccmcnt of Surface-parallel Stratitied Systems .. .. . . . 13 1

8.1 Generai Recommcndations . . ............ . .. . ... . ... ... . . . . . 13 1 8.2 Design and Engineering Notes . . . .. . . . .. . . . . . .. . ...... . ..... 132 8.3 Analyses . ...... . ... . . . ... . . .. . . . . . . .. . . .. . .. . . . . . . .. . .. . . 133 8.3.1 Principles .. . . ......... . .. . .... . .. . .. . . . .. .... . .. . . .. . . . . . 133 8.3.2 Analysing the Stability ofthe lnclined Liner System . . . . .... . . . 134 8.3.2 .1 Actions and EtTects ..... . .. . .. . . .. . . .. . .................... 136 8.3.2.2 Resistances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8 8.3.3 Structural Resistance of Reinforcement ... . .......... . ....... 139 8.3.4 Anchorage . .. ..... .. .. . .. . .. . . . .. . ... . . .. . .. . . .... . .. .. . . 140 8.4 Bibliography ... . .. . .. . . . . . . . . . ....... . . .. . .. . . .. . . .. .. . .. 141 8.5 Example of Landfill Capping using Geosynthetic

Reinforcement . . ...... . .. . .. . .... . ..... . . . ... . . .. . . .... . . 142 8.5.1 Geometry, Soil Mechanics Parameters, Geosynthetic Properties

and Data for a Selected Construction Vehicle ..... .. ... . . .. ... 142 8.5.1.1 Geometry of the Liner System in t h e S lope .... . ... . .......... 142 8.5.1.2 Characteristic So il Mechanics Jnput Values . ....... . . . .. . . . . .. 142 8.5.1.3 Geosynthetics .................... . .... . . ..... .. . ........ . 142 8.5.1.4 Data fora Selected Tracked Vehicle ...... . ... . ... . . . . . .. . .. . 143 8.5.1.5 Construction State Definition . .. .. . . . . .. . . .. . . .. . ........... 143 8.5.2 Stability Analysis ........ . ...... . ... . ... .. .. . . . .. . . . ... ... 143 8.5.3 Analysing Reinforcement Failure .... . .. . . ...... .. ....... . .. 146 8.5.4 Designing the Anchor Trench ........ . ....... . . .. . . .. . .. . .. . 146 8.5.4.1 Anchor Trench Geometry . .. . .. .. . . . . . . . . . ............. . . .. 146 8.5.4.2 Friction Resistance l nput Values .... . .... . .... .. . . ....... . .. 147 8.5.4.3 Safety Against Failure of the Anchor Trench ........... . .. . .. . 147

Il 8.5.4.4

9 Il

Analysing Failure ofthe Top of the Embankment . . . .......... 149

Reinforced Ear th Structures over Point or Linear Bearing Elements . ... .. .. . .......... .. ... . . . ... . . 151

9.1 Definitions .. . .. . ... . ............... . ....... . ............. 1 51 9.2 Applications and Modus Operandi . . .. . ....... . .. .. .. . .. . .. . 153 9.2.1 Applìcations .... . .... . .. . .. . .... . .. . . . .. . .... . ...... . .. . .. 153 9.2.2 Modus Operandi . ... . ................................ . . . .. 154 9.3 Design and Engineering Recommendations .......... . ........ 155 9.4 Actions and Resistances .......... . ...... . ...... . ... . ... . .. 157 9.5 Point and Linear Bearing Elements . .. . .. . . . ................. 158 9.6 Analysing the Reinforced Earth Structure .... . ..... . ... . . .... 158 9.6.1 Generai Recommendations ...... . .... .. . ... .. . ..... . .... . .. 158 9.6.2 Effect Situations ...... . ............. . ... . ... .. .. . .. . . . .. . . 159 9.6.3 Characteristic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 9.6.3.1 Principles . .. . .. . . . ..... . ........... . .... . .. . ............. 160 9.6.3.2 Stress crzo,k between the Bearing Elements .. . .... . .. . . .. . .... . 160

XIV

9.6.3.3 9.6.3 .-l

9.6.3.5 9.6.4

9.6.5

9.7 9.7.1 9. 7. 1.1 9.7.1.2 9.7.1.3 9.7.1.4 9.7.2 9.7.2.1 9.7.2.2 9.7.2.3 9.7 .2.4 9.8 9.8. 1 9.8.2 9 .8.3 9.9 9.10

9.10.1

9.10.2 9.10.2. 1 9.10.2.2 9. 10.3 9.10.3. 1 9.10.3.2 9.10.4 9. 10.4.1 9.1 0.4.2 9.1 0.5 9. 10.5.1 9. 10.5.2 9.10.6 9. 10.7 9. 10.8

Stress cr,,_k onthe Bearing [lements .... . ....... . .......... . . 164 Sprcading Forccs for lnclined Surface of Reintorced Earth Structure . . .. . . . .. ...... . . .. . . ..... . .... 165 Effccts on the Geosynthctic Reinforcement. . ................. 165 Analysing Eftèct on the Gcosymhctic Re inforcement using Numerica! Methods ....... ........... ....... ... ........... 173 Analysing EITects on Gcosynthetic Reinforcement fo r Oynamic Actions . . .. . .. ....... ....... .. . ................. ......... 174 Analyscs and Des ign .... . .. ... . . . . .... ..... . . . . ........... 174 Analysing Bearing Capacity .... . . . . ...... . .. .......... ..... 174 Generai Recommendations ........ .............. ........... 174 Analysing the Geosynthetic Reinforcement .. . ........... ..... 174 Analysing Bearing Elemenrs . ............. . ................. 175 Analysing Overall Stability ...... . . .. . . . . ................ . .. 176 Serviceability Limit State Analysis . ....... . .. . . . . ........... 176 Generai Recommendations . .. .. ..... ... .... ...... .......... 176 Deformations in the Reinforced Earth Structure ... . ...... . .. .. 176 Deformati an of Bearing Elements .... .... . . . .. ..... , ...... . . 177 Analysing Overall Deformations .... .. . .. . ...... ...... . ..... 177 Notes on Execution ............ . . ...... . ... . ....... ........ 177 Enabling Works . ................. ...... ........... . . . . .. . . 177 Point and Linear Bearing Elements . ......... .. .. ............ 177 Reinforced Earth Structures ........... ... .. . . . ............. 178 Bibliography ............. . ........... .. .................. 178 Design Example: Reinforced Earth Structures over Poim or Linear Bearing Elements ........ ..... . . .. . ............ .. 180 Geometry, Loads, Soil Mechanics Parameters, Reinforcement and Effect Situation Parameters ....... . ...... .... .... . . .. ... 180 Eftèct Situation 1: Construction State (t1 = l O h) ........ . . .... 183 Load Redistribution in the Reinforced Earth Structure ...... ... 183 Characteristic Effects in the Geosynthetic Reinforcement ..... . 185 Effect Siruation 2: Constn1ction State (t? = 500 h) . .... .. . . .... 189 Load Redistribution in the Reinforced Éarth Structure . . .. . .. . . 189 Characteristic Effects in the Geosynthetic Reinforcement ..... . 191 Effect Situation 3: Fina! State (t3 = 1,000,000 h) .............. 193 Load Redistribution in the Reinforced Earth Structure .... .. . .. 193 Characteristic Effects in the Geosynthetic Reinforcement . .. . .. 194 Special Case: Loss ofSubgrade Reaction (t4 = 1,000,000 h) ... . 196 Load Redistribution in the Base Course . . . . . . . . . . . . . . . . . . . . . . 196 Characteristic Effects in the Geosynthetic Reinforcement . . ... . 196 Design Values ofEtfects in the Geosynthetic Reinforcement . .. . 198 Design Values of Resistances ... .............. ............ .. 199 Analysing Bearing Capacity ........ ........... ............ . 200

xv

10

IO. l 10.2 10.2.1 10.2.2 10.3 10.3.1 10.3.2 10.3.3 10.3.4 l 0.4 l 0.5 10.6 10.6.1 10.6.2 10.6.3 10.6.4 l 0.6.4.1 10.6.4.2 10.6.4.3 10.6.5 10.6.6 10.6.6.1 10.6.6.2 10.6.6.3 10.7 10.8 10.9 l 0.9.1 l 0.9.2 10.9.2.\ 10.9.2.2 10.9.2.3 10.9.2.4 10.9.2.5 10.9.2.6

11

11.1 11.2 11.2.1 11.2.2 11.2.2.1 11.2.2.2

XV!

Foundation Systems using Geosynthetic-cncascd Colum ns . . 20 l

Ddinitions .. ........... . . .. ... .... . . . .. . . ... ... . .... . ... . 201 Modus Operandi and App lications . .. ... . ....... .. . .. . . . . . .. . 203 Modus Operandi ....... ......... . . . . ... . ..... .. . . . . .. . .... 203 Applications . . . .. ..... . .. . . .. ... .. .......... . .. . .. . . . . ... . 204 Manufacturing Methods . . .. .. . ........... ..... .. . .... . .. ... 206 Genera i Recommendations . . . ....... ....... .. . . . .......... . 206 Excavation Method . . . . ..... . ....... .. ...... ..... ... . .. . . .. 206 Displacement Methods .. . . . .. . .. . ..... . . . ... .. .. ...... ..... 207 Method Selection .. ... .. ... . ........... . . .... . ...... .. . . .. 207 Design Rccommendations and Engineering Notes . .. . ... . . .... 209 Bui lding Materials .......... ... . .. . . ........... ... . .. . .... 21 O Notes o n Analysis and Design .. . . .... . . .... .. ... . .. ... . . . .. 21 O Genera i Recommendations . . .. . ...... .... . . .. . . .... . .. . ... . 21 O Actions and Resistances .............. .. ....... . ...... . ... . 2 1 l Designing the Horizontal Geosynthetic Reinforcement. . ....... 2 11 Column Design . ............ .... . .. ............ . .. ... . . ... 2 12 Analysis Mode! ...... .... .... . ..... ......... ......... . .... 2 12 Analysis Methods .... . . . ..... ... .. . .. . . . .. . ............. .. 21 4 Analysing t h e Transfer of Circumferential Tensile Forces . ..... 217 Analysing Overall Stability .... ....... ......... .. . ..... . . ... 218 Serviceability Limit State Analysis .................. . ...... . 219 Determining Settlement ..................... . .... ...... .... 219 Cyclic-dynamic Actions .. . . . . ........... ........ ... . ... ... . 2 19 Overall Deformations ........ ..... ......................... 220 Inspection Criteria, Tolerances and Quality Assurance .... . .. .. 220 Bibliography ....... . . .......... .. . . ...... . ... ......... . . . 222 Worked Example: Geotexti le-encased Columns ............... 222 lnput data ....... . . . . ...... .... . ... . . ...... . . .. .. . ........ 222 Analysis ...... ........... . .... . . .. ........ .. .... . ........ 223 Determining Primary Stresses ... .. ................. . ....... 223 Assuming the Load Redistribution Factor E .... .... . .... ..... 224 Determ ining the Stiffness Parameter ........ . .. . . ........ .... 224 Deformation at the Colurnn Edge ........ ......... .......... 224 Determining Sett1ement. ....... ....... ......... . . .. . .. ..... 225 Analysing Circumferential Tensile Force ...... . .... .. .... . ... 225

Overbridging Systems in Areas Prone to Subsidence . ....... 227

Generai Recommendations ................... .. .. ... . ..... . 227 Design ..... ... .. . ............. ...... . .. . ...... .... . .. .... 228 Princip les and Definitions .... .... . . ........... .. .. ... ...... 228 Design Notes .. ........................................... 231 Explanatory Report ... .. . . .. . ....... . . .. ............ . ...... 23 l Determining the Width ofthe Stabilised Area ....... ...... .... 232

11 .2.3 11.2.3.1 l 1.2.3.2 l 1.2.3.3 l 1.2.3.4 11.2.3.5 11.2.4 J 1.2.5 11.2.6 11.3 l 1.3. 1 11.3.2 11.3.2.1

l 1.3.2.2

l l .3.2.3 11.3.2.4 11.3.2.5 lJ .3.2.6 l 1.3.3 11.4 11.5 11.6 11.7 11.7.1 11.7.2 11.7.3 11.7.4 11.7.4. 1 11.7.4.2 11 .7.4.3 11.7 .4.4 11.7 .5

11.7.5. l 11.7.5.2

l 1.7.5.3

11 .7.5.4

11.7.6 11.7.7 11.7.7.1

Ground and .\1atcriab . ............. ... . ....... ..... ... . . ... 235 Excavarion Leve! .............. ..... .. . .. . .... . .. ......... 235 Composite base course Marerials ....... ....... .. ....... . .. . . 235 Geosynthetic Reinlorccment. ..... .. . ......... ............ .. 235 Bridging Zone Material s .. .. . .. ... . . .. . .... . .. . . ... . .. .. .. . 235 Subgrade .. .................. . ... . .... . .. . ... .. ... . .. . .... 235 Load Assurnptions and Load Cases . . . . . . . . . ...... . ... . . . . ... 23 5 Allowable Deformations ........... . . .. .. . . . . ..... . .... . .. . 236 Strucmral Models . . ....... . ... . .... . . . . .. . .. . . . ..... ..... . 236 Analyses . .. .. . . ..... .... .... . . . ... . ..... . . ... . . . ....... . . 239 Analysis Principles .... .. ........... .... . . ..... . .. . .... .... 239 Design ... . . . . ....... . .......... . ..... . .. . .... .. . ...... . . . 242 Determining the Tensile Stress Design Yalues using the B.G.E. Method ....... ... . .. . ........ ....... ...... 242 Determining the Design Value ofthe Tensile Stress Based on the R.A.f.A.E.L. Method [8) .. ... .. . . . .... . .. ...... 247 Special Methods ......... . ... . . .. . .. . .. ...... . .. . ......... 249 Determining the Required Short-term Tensile Strength .. . .. . ... 250 Analysing Anchorage .Lengths . . . ...... . .. . . ... . . ... . .. ... . . 250 Analysing Overlap Lengths . .. . .. .. ..... .... . . . . .. ........ . . 251 Safety Theory Analysis ...... . . .. . ... . . ... ... . .. . .... . ..... 252 Applying the Observational Method .. . .. . .. ....... .. ..... . .. 253 Notes on Execution . . .. . . .......... . . .. . .. . . ........ .... ... 254 Bibliography .... . ................... . .. . . .. . . ............ 255 Worked Analysis Example l ............... . ................ 256 Specifications . ......... ... ... . .. . . .. . . ............... .. . . 256 Allowable Reinforcement Sag an d Stra in . .. . . ...... ...... .... 257 Preselecting the Geosynthetics .. . . ..... . .. . . . . ............. 257 Determining the Actions ..... .. . ..... . . ....... . . . .... .. . . .. 258 Normal Stresses . ... ...... ... . . . . . . .. . . . .. .......... . . . . .. . 258 Load Component Factors . ..... ..... . . .. . . . .... ... . .. .. .. . . 258 Design Values ofHorizontal Te nsile Forces .. . . . ... .......... 258 Design Values of Actions ..... . . . . ... . ..... ... ... ........... 259 Determining the Design Values of the Resistances in the Macbine and Cross Machine Direc.tions ...... ......... . 259 Adopted Reinforcement. ..... . ........ . .. . . . ............... 259 Design Value ofthe Tensi le Strength, Criterion l: Reinforcement Creep Failure .. . ....... . .. . . .. . . . 259 Design Value of the Tensile Strength, Criterion 2: Reinforcement Creep Strain . . .. . . .. . . ... . ....... 260 Governing Design Value of the Tensile Strength of the Reinforcement . . . .. .. . ... . . .. . .. . . . . ..... . . . . ... . .. . 260 Analysing Adequate Tensile Strength . . .... ... .......... . . ... 260 Analysing Anchorages .. . ............. .. . . . .. ............ . . 260 Specifications ......... . ... . _ . . .... . . . .... .. . .. . . ......... 260

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11.7.7.2

11.7.7.3

11 .7.7.4

11.7.8 11.7.8.1 11.7.R.2 11.8 11.8. 1 11.8.2 11.8.3 11.8.3.1 11.8.3.2 11.8.4

11.8.4.1 11.8.4.2 11.8.4.3

11.8.4.4

11.8.4.5

11.8.4.5 11.8.6 11.8.6.1

ti 11 .8.6.2

11.8.7 11.8.7.1 11.8. 7.2

12

12.1 12.2 12.3 12.4 12.5 12.6 12.6.1 12.6.1. 1

XYlll

Required Re in1òrccm..:m Am:horage Lcngths in Machine Direction Outside of the Sinkholc-prone Area .... .. 260 Required Reinforcement Anchorage Lcngths in Cross Machine Direction Outside of the Sinkhole-prone Area .. .......... . . ... 261 Required Reinforccment Anchorage Lengths in Cross :vtachine Direction 1nsidc of thc Si nkhole-prone Area ... .. .. ....... . . .. 261 Overlap Ana lysis ... ......... ..... . ......... ..... . .... ..... 26 1 Required Overlap Lcngth in Machine Direction ............ . .. 261 Required Overlap Width in Cross Machine Dircction ..... . ... . 26 1 Worked Analysis Example 2 . .. ... .. . .. .. ... . .. .......... ... 26 1 Specifications ............ ...... . ........ . . ............. . . 26 1 Allo':<.'able Reinforccmen t Sag and Strain .. ............ .... .. . 262 Determining thc Actions .. .. .. . .. . ...... ...... ............. 262

ormai Stresses . . .. .... ............ ..... .... ............ .. 262 Design Va tue of t h e Actions o n the Geosynthetic Reinforcement 263 Determining the Design Values ofthe Resistances in the Machine Direction ..... . .......... ........ . ..... ... .. 263 Adopted Reinforcement. .... . .. . ................ . .... ... ... 263 Analysing Extreme Anisotropy . . . . . ... .. . . . .... .. ... • .. • ... 263 Design Value of the Tensile Strength, Criterion l : Reinforcement Creep Fai1ure ....... . ............ 264 Design Value ofthe Tensile Strength, Criterion 2: Reinforcement Creep Strain . .... ............ ... . 264 Governing Design Value ofthe Tensile Strength of the Reinforcement . .. . .. ....... ........ . .. ............. . 264 Analysing Adequate Tensile Strength .. . . ................ .... 264 Analysing Anchorages ........... . ........ .......... . . ..... 264 Required Reinforcement Anchorage Lengths in Machine Direction Outside ofthe S inkhole-prone Area ...... 265 Required Re inforcement Anchorage Length in Cross Machine Direction . . .. . . .. . ... ........ . ... . .. . . .. . 265 Overlap Ana1ysis ....... . . .. . . . .. . . ............. . ....... . .. 265 Overlap Length in Machine Direction ....... . ........... . . . .. 265 Overlap Length in Cross Machine Direction .................. 265

Dynamic Actions on Geosyntbetic-reinforced Systems ...... 267

Generai Recommendations ........... ............. . . ....... 267 Dynamic Actions ....... .... .. . .. .. ..... . . .. . .. ...... . .... . 267 Dynamic Effects .... . ... . ..... . . .. . . ..... . ......... . ...... 269 Resistances . .. . .... ... ...... . .. . . . .... .............. . . . . .. 269 Dynamic Design Cases . .. . ... . .. . . . ............. . . .. . ..... 269 Dynamic Actions .. . ....... . .. . .... .. .................... . . 272 Dynamic Actions- Li ve Loads . . .. . . .. . . . ...... .... ..... .. . 272 Adopting Li ve Loads .. . ...... . . .... ..................... . . 272

12.6.1 .2 12.6.1.3 12.6.2 12.6.3 12.7 12.7.1 12.7.2 12.7.3 12.R 12.8. 1 12.8. 1.1 12.8.1.2 12.8.1.3 12.8.2 12.8.2. 1 12.8.2.2 12.8.2.3 12.9 12.9.1 12.9. 1.1 12.9. 1.2 12.9.1.3 12.9.1.4 12.9.2 12.9.2. 1 12.9.2.2 12.9.2.3 12.10 12.11

13

14

Allocation to Dynamic Dt.:sign Cases - Live Loads .. .... .... . . 274 Dt.:sign Recommcndations ......... .. ... ... .............. . .. 275 Dynamic Actions - Explosions. lmpact. Avalanchcs ........... ?.76 Dynamic Actions Seismic Loads . . .. . .. . . . .. .... . . .. ...... 277 Determining the Dynarnic Efìècts on the Geosynthctics . . ...... 278 Dynamic Design Case l ..... . ..... .. . . ............... .. .... 278 Dynamic Design Case 2 . ......... . • .. . ...... . .. . .. . .. . . .. . . 278 Dynamic Design Case 3 ...... .. .. . .. . . .. .. .... .... . .. . .. ... 278 Dctermining the Resistances for Dynamic Actions ........ .... 279 Pull-out Resistance of Reinforcement. .. ............ .. . • ..... 279 Dynamic Design Case l ....... . ......... . . . .... . ... .. ..... . 279 Dynamic Design Case 2 .... . .. .......... .. . . ........... .. .. 279 Dynamic Design Case 3 ........... .... .......... .. ......... 280 Structural Resistance of Reinforcement ....... ............... 280 Dynamic Design Case l .. ... ... ...... ............... . .. . ... 280 Dynamic Design Case 2 .............. . ......... , ........... 280 Dynamic Design Case 3 ....... ......... .. . ........... ...... 280 Demands on Building Materials under Dynamic Loads ........ 281 Fili Soil . . ..... . . ................................... . ..... 28 1 Grain Sizes . ....... ............................. ...... .... 281 Grain Shape, Grain Strength ..... ........... ................ 281 Fili Soil Friction Coefficient ............ . ................... 282 Relative Compaction . . ....... ..... .................. . ..... 282 Geosynthetics ................ .. .... . ..................... 282 Determining F atigue Behaviour ............................. 282 Determining Damage ....... . ........... .. . . ............... 284 Determining the Geosynthetic/Fill Soil Composite Coefficient. . 284 Bibliography . . ..... ... .......................... ... .. .. .. 285 Diagrams .. ....................... . . .. . . ........ . .. • ..... 288

Figures .... . .. . . .................. . ...................... 307

Tables ............................. . . . ................... 313

Advertising List ............................... .. . . . ... ............ 315

XIX