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iii TABLE OF CONTENTS LIST OF FIGURES ....................................................................................................................... vi LIST OF TABLES ......................................................................................................................... xi CHAPTER 1. INTRODUCTION ................................................................................................... 1 Introduction ................................................................................................................................. 1 Objective ..................................................................................................................................... 1 Research Scope and Approach ................................................................................................... 1 Organization of the Report ......................................................................................................... 4 CHAPTER 2. SYNTHESIS OF CURRENT KNOWLEDGE ....................................................... 5 Laboratory Characterization of Granular Materials with Geosynthetics .................................... 5 Modeling of Pavements with Geosynthetics .............................................................................. 6 Design Methods for Pavements with Geosynthetics .................................................................. 7 CHAPTER 3. RESEARCH PLAN ................................................................................................. 9 Full-Scale Laboratory Testing .................................................................................................... 9 Triaxial Laboratory Testing ...................................................................................................... 10 Finite Element Modeling .......................................................................................................... 11 Development of ANN Models of Critical Strains and Stresses ................................................ 11 Performance Data Collection of In-Service Pavement Sections with Geosynthetics ............... 12 CHAPTER 4. EXPERIMENTS, MODELING, AND FINDINGS .............................................. 13 Introduction ............................................................................................................................... 13 Geosynthetic Application and Reinforcement Mechanisms ..................................................... 13 Available Test Methods for Evaluating Geosynthetic Properties Related to Pavement Performance .............................................................................................................................. 14 Selection of Test Methods for Determining Geosynthetic Properties ...................................... 15 Direct Tension Test to Determine Geosynthetic Sheet Stiffness .......................................... 15 Pullout Test to Determine Geosynthetic-Aggregate/Soil Interfacial Properties ................... 16 Laboratory Methodology for Quantifying Influence of Geosynthetics .................................... 17 Influence of Geosynthetics on Cross-Anisotropic Properties of UGMs ............................... 17 Influence of Geosynthetics on Permanent Deformation Properties of UGMs...................... 24 Analytical Model for Quantifying the Influence of Geosynthetics .......................................... 30 LST Test on Pavement Layers with Geosynthetics .................................................................. 34 Experimental Plan and Setup ................................................................................................ 35 Data Analysis Methodologies ............................................................................................... 43 Flexible Pavement ................................................................................................................. 43 Rigid Pavement ..................................................................................................................... 65 Finite Element Modeling of Pavements with Geosynthetics .................................................... 77 Characterization of Materials Used in LST Test .................................................................. 80 Development of Nonlinear Cross-Anisotropic User-Defined Material Subroutine .............. 85 Development of Goodman Model Friction Subroutine ........................................................ 87 Numerical Modeling Techniques for Geosynthetic-Reinforced Pavement Structures ......... 88 Effect of Geosynthetic Reinforcement on Pavement Responses .......................................... 89 Parametric Study of Material Properties on Pavement Performance .................................... 93 Comparison of Finite Element Simulations with LST Measurements ................................. 98 ANN Approach for Predicting Pavement Performance .......................................................... 105 Experimental Computational Plan for ANN Models .......................................................... 106 Development of ANN Models ............................................................................................ 107Â
iv Determination of Modified Material Properties.................................................................. 113Â Prediction of Pavement Performance .................................................................................. 117Â Validation of the Proposed ANN Approach ....................................................................... 120Â CHAPTER 5. INTERPRETATIONS, APPRAISAL, AND APPLICATIONS ......................... 124Â Introduction ............................................................................................................................. 124Â LST Testing Program .............................................................................................................. 124Â Measurement of Geosynthetic-Aggregate/Soil Interfacial Slippage ...................................... 127Â Determination of Geosynthetic-Aggregate/Soil Interfacial Properties ................................... 129Â Impact of Geosynthetics on Cross-Anisotropy and Permanent Deformation of UGMs ........ 129Â Mechanistic-Empirical Permanent Deformation Model for Unreinforced and Geosynthetic-Reinforced UGMs ............................................................................................ 132Â Analytical Model for Quantifying Influence of Geosynthetics .............................................. 134Â Development of Finite Element Model for Geosynthetic-Reinforced Pavement ................... 135Â Predictions of Geosynthetic-Reinforced Pavement Performance ........................................... 136Â CHAPTER 6. SUMMARY AND SUGGESTED RESEARCH ................................................. 145Â Summary ................................................................................................................................. 145Â Suggested Research ................................................................................................................ 146Â REFERENCES ........................................................................................................................... 148Â ATTACHMENT A. STANDARD METHOD OF TEST FOR DETERMINING THE PERMANENT DEFORMATION PROPERTIES OF GEOSYNTHETIC- REINFORCED AND UNREINFORCED GRANULAR MATERIAL ............................... 153Â ATTACHMENT B. STANDARD METHOD OF TEST FOR DETERMINING THE CROSS-ANISOTROPIC RESILIENT MODULUS OF GEOSYNTHETIC- REINFORCED AND UNREINFORCED GRANULAR MATERIAL ............................... 157 FINAL REPORT APPENDICES ............................................................................................... 165Â APPENDIX A. REVIEW OF AVAILABLE TEST METHODS FOR DETERMINING PERFORMANCE-RELATED GEOSYNTHETIC PROPERTIES ..................................... A-1Â APPENDIX B. DETERMINATION OF GEOSYNTHETIC-AGGREGATE INTERFACIAL PROPERTIES USING PULLOUT TEST ................................................. B-1Â APPENDIX C. LABORATORY EVALUATION OF INFLUENCE OF GEOSYNTHETICS ON CROSS-ANISOTROPY AND PERMANENT DEFORMATION OF UNBOUND GRANULAR MATERIAL ......................................... C-1Â APPENDIX D. ANALYTICAL MODEL FOR QUANTIFYING INFLUENCE OF GEOSYNTHETICS .............................................................................................................. D-1Â APPENDIX E. INSTRUMENTATION PLANS FOR FLEXIBLE PAVEMENT EXPERIMENTS .................................................................................................................... E-1Â APPENDIX F. SUMMARY CHARTS FOR FLEXIBLE PAVEMENT EXPERIMENTS ....... F-1Â APPENDIX G. FLEXIBLE PAVEMENT EXPERIMENTS: COMPARISON OF TEST MEASUREMENTS .............................................................................................................. G-1Â APPENDIX H. INSTRUMENTATION PLANS FOR RIGID PAVEMENT EXPERIMENTS ................................................................................................................... H-1Â APPENDIX I. ANALYSIS METHODOLOGIES OF LST TEST DATA................................... I-1Â APPENDIX J. SUMMARY CHARTS OF RIGID PAVEMENT EXPERIMENTS .................. J-1Â APPENDIX K. RIGID PAVEMENT EXPERIMENTS: COMPARISON OF TEST MEASUREMENTS .............................................................................................................. K-1Â
v APPENDIX L. CHARACTERIZATION OF MATERIALS USED IN LST TEST ................... L-1Â APPENDIX M. COMPARISON OF FINITE ELEMENT SIMULATIONS WITH LST MEASUREMENTS ............................................................................................................. M-1Â APPENDIX N. DEVELOPMENT OF ARTIFICIAL NEURAL NETWORK MODELS FOR PREDICTING GEOSYNTHETIC-REINFORCED PAVEMENT PERFORMANCE ................................................................................................................. N-1Â APPENDIX O. VALIDATION OF ARTIFICIAL NEURAL NETWORK APPROACH FOR PREDICTING GEOSYNTHETIC-REINFORCED PAVEMENT PERFORMANCE ................................................................................................................. O-1Â APPENDIX P. LIST OF GEOSYNTHETIC-REINFORCED IN-SERVICE PAVEMENT SECTIONS IDENTIFIED FROM LONG-TERM PAVEMENT PERFORMANCE (LTPP) DATABASE AND TEXAS PAVEMENT MANAGEMENT INFORMATION SYSTEM (PMIS) ................................................................................................................... P-1 APPENDIX Q. EXAMPLES OF PROGRAM RUNS OF THE COMPOSITE GEOSYNTHETICâBASE COURSE MODEL .................................................................... Q-1
vi LIST OF FIGURES Figure 1.1. Compatibility of Proposed Program with AASHTOWare Pavement ME Design ................................................................................................................................. 3Â Figure 4.1. Mechanisms of Geosynthetics in Pavement ............................................................... 14Â Figure 4.2. Schematic Plot of the Pullout Test ............................................................................. 16Â Figure 4.3. Pullout Force versus Geosynthetic Displacement in a Pullout Test ........................... 17Â Figure 4.4. Schematic Plot of Aggregate Specimens with/without Geosynthetic ........................ 18Â Figure 4.5. Configuration of Rapid Triaxial Test ......................................................................... 19Â Figure 4.6. Effect of Stress Level on Reduction of Permanent Strain .......................................... 24Â Figure 4.7. Illustration of the Stress-Related Terms in the Proposed Model ................................ 26Â Figure 4.8. Comparison of Lab-Measured and Proposed Model-Predicted Permanent Deformation Curves .......................................................................................................... 27Â Figure 4.9. Validation of Prediction Accuracy of Proposed Permanent Deformation Model ................................................................................................................................ 28Â Figure 4.10. Effect of Type of Geosynthetic on Permanent Deformation of UGM ..................... 29Â Figure 4.11. Effect of Location of Geosynthetic on Permanent Deformation of UGM ............... 29Â Figure 4.12. Schematic Plot of Geosynthetic Reinforcement on UGM Specimen ....................... 31Â Figure 4.13. Comparison of Resilient Moduli Predicted by Analytical Models with Measured Values ............................................................................................................... 34Â Figure 4.14. FWD Loading Plate Used in the LST Experiments: (a) Top View; (b) Bottom View ............................................................................................................... 36Â Figure 4.15. Plastic Sheet Covering the Wave-Absorbing Material in the LST ........................... 36Â Figure 4.16. Completed Large-Scale Test Setup for Flexible Pavement Experiment .................. 37Â Figure 4.17. Instrumentation Plan for Flexible Pavement Experiment 4: (a) Profile View at X = 0 inch; (b) Plan View at Z = 0 inch ........................................................................ 39Â Figure 4.18. Instrumentation Plan for Rigid Pavement Experiment 9: (a) Profile View at Y = 0 inch; (b) Plan View at Z = 0 inch ........................................................................... 40Â Figure 4.19. Placement of the 4-inch Earth Pressure Cell in the Subgrade .................................. 41Â Figure 4.20. (a) In-Place Asphalt Strain Gauge; (b) Final In-Place Asphalt Strain Gauge with Temperature Sensor .................................................................................................. 42Â Figure 4.21. LST Configuration for Flexible Pavements with Thin CAB (Experiments 1, 3, and 5) Showing Only Earth Pressure Cells across Geosynthetic .................................. 47Â Figure 4.22. Vertical Stresses at the Centerline of the Loading Plate for Thin CAB Layer (Experiments 1, 3, and 5) .................................................................................................. 48Â Figure 4.23. Vertical Stresses at the Edge of the Loading Plate for Thin CAB Layer (Experiments 1, 3, and 5) .................................................................................................. 49Â Figure 4.24. Horizontal Stresses at the Edge of the Loading Plate for Thin CAB Layer (Experiments 1, 3, and 5) .................................................................................................. 50Â Figure 4.25. LST Configuration for Flexible Pavements with Thick CAB (Experiments 2, 4, and 6) Showing Only Earth Pressure Cells across Geosynthetic .................................. 50Â Figure 4.26. Vertical Stresses at the Centerline of the Loading Plate for Thick CAB Layer (Experiments 2, 4, and 6) .................................................................................................. 51Â Figure 4.27. Vertical Stresses at the Edge of the Loading Plate for Thick CAB Layer (Experiments 2, 4, and 6) .................................................................................................. 52Â Figure 4.28. Horizontal Stresses at the Edge of the Loading Plate for Thick CAB Layer (Experiments 2, 4, and 6) .................................................................................................. 53Â
vii Figure 4.29. LST Configuration for Flexible Pavements with Thin CAB (Experiments 1, 3, and 5) Showing Only the Instrumentations on and around Geosynthetic .................... 54Â Figure 4.30. LST Configuration for Flexible Pavements with Thick CAB (Experiments 2, 4, and 6) Showing Only the Instrumentations on and around Geosynthetic .................... 55Â Figure 4.31. Horizontal Strains in the Geosynthetic ReinforcementsâFlexible Pavements: (a) Experiment 3 (geogrid); (b) Experiment 5 (geotextile) ........................... 56Â Figure 4.32. Horizontal Strains in the Geosynthetic ReinforcementsâFlexible Pavements: (a) Experiment 4 (geogrid); (b) Experiment 6 (geotextile) ........................... 57Â Figure 4.33. Tensile Strains at the Centerline of the Load and at the Bottom of the AC Layer (Experiments 1, 3, and 5) ........................................................................................ 57Â Figure 4.34. Tensile Strains at the Centerline of the Load and at the Bottom of the AC Layer (Experiments 2, 4, and 6) ........................................................................................ 58Â Figure 4.35. Vertical Displacements of the Geosynthetic and Adjacent Unbound Material in Experiments 3 and 5 for Various Load Levels: (a) 9 kip; (b) 12 kip; (c) 16 kip .......... 60Â Figure 4.36. Horizontal Displacements of the Geosynthetic and Adjacent Unbound Material in Experiments 1, 3, and 5 for Various Load Levels: (a) 9 kip; (b) 12 kip; (c) 16 kip ........................................................................................................................... 61Â Figure 4.37. Horizontal Slippage of the Geosynthetic and Adjacent Unbound Material in Experiments 3 and 5 for Various Load LevelsâFlexible Pavements .............................. 62Â Figure 4.38. Vertical Displacements of the Geosynthetic and Adjacent Unbound Material in Experiments 4 and 6 for Various Load Levels: (a) 9 kip; (b) 12 kip; (c) 16 kip .......... 63Â Figure 4.39. Horizontal Displacements of the Geosynthetic and Adjacent Unbound Material in Experiments 2, 4, and 6 for Various Load Levels: (a) 9 kip; (b) 12 kip; (c) 16 kip ........................................................................................................................... 64Â Figure 4.40. Horizontal Slippage of the Geosynthetic and Adjacent Unbound Material in Experiments 4 and 6 for Various Load LevelsâFlexible Pavements .............................. 65Â Figure 4.41. LST Configuration for Rigid Pavements (Experiments 7, 9, and 10) Showing Only Earth Pressure Cells across GeosyntheticâProfile View ....................................... 68Â Figure 4.42. LST Configuration for Rigid Pavements (Experiments 7, 9, and 10) Showing Only Earth Pressure Cells across GeosyntheticâPlan View at 8 inches below Pavement Surface .............................................................................................................. 68Â Figure 4.43. Vertical Stresses at the Centerline of the Loading Plate for Rigid Pavements (Experiments 7, 9, and 10âDry and Wet) ....................................................................... 69Â Figure 4.44. Vertical Stresses at Two Similar Locations in the CAB across the Joint and at 8 inches from the Centerline of the Loading Plate for Rigid Pavements (Experiments 7, 9, and 10âDry and Wet) ....................................................................... 70Â Figure 4.45. Vertical and Horizontal Stresses at the Edge of the Loading Plate in the X-direction (Parallel to the Edge of the PCC Slab) for Rigid Pavements (Experiments 7, 9, and 10âDry and Wet) ....................................................................... 71Â Figure 4.46. LST Configuration for Rigid Pavements (Experiments 7, 9, and 10) Showing Only Strain Gauges on GeosyntheticâProfile View ....................................................... 72Â Figure 4.47. LST Configuration for Rigid Pavements (Experiments 7, 9, and 10) Showing Only Strain Gauges on GeosyntheticâPlan View at 10 inches below Pavement Surface .............................................................................................................................. 72Â Figure 4.48. Horizontal Strains in the Geogrid Reinforcement (Experiment 9)âRigid Pavement (Dry and Wet) .................................................................................................. 73Â
viii Figure 4.49. Tensile Strains in the X-direction (Parallel to the Edge of the PCC Slab) at the Centerline of the Load and at the Bottom of the PCC Layer (Experiments 7, 9, and 10) .............................................................................................................................. 74Â Figure 4.50. LST Configuration for Rigid Pavements (Experiments 7, 9, and 10) Showing Only the LVDT Used for Assessing Slippage at the PCC EdgeâProfile View .............. 76Â Figure 4.51. LST Configuration for Rigid Pavements (Experiments 7, 9, and 10) Showing Only the LVDT Used to Assess Slippage at the PCC EdgeâPlan View at 6 inches below Pavement Surface ........................................................................................ 76Â Figure 4.52. PCC-CAB Interface Slippage at the Edge of the PCC Slab (Experiments 7, 9, and 10): (a) Dry Condition; (b) Wet Condition ............................................................ 77Â Figure 4.53. Typical Geosynthetic-Reinforced Flexible Pavement Structure in LST Test .......... 78Â Figure 4.54. Meshed Geosynthetic-Reinforced Pavement Structure in ABAQUS ...................... 78Â Figure 4.55. Typical Geosynthetic-Reinforced Rigid Pavement Structure in LST Test .............. 79Â Figure 4.56. Meshed Geosynthetic-Reinforced Rigid Pavement Structure in ABAQUS ............ 80Â Figure 4.57. Comparison between the Measured Dynamic Moduli and the Fitted Dynamic Moduli ............................................................................................................... 83Â Figure 4.58. Direct Tension Test for Determining Sheet Stiffness of Geosynthetics ................... 84Â Figure 4.59. Relationships between Tensile Force and Tensile Strain for Geosynthetics ............ 85Â Figure 4.60. Flowchart of the Developed UMAT Subroutine ...................................................... 87Â Figure 4.61. Simulation of Lateral Confinement in Geosynthetic-Reinforced Pavement Structure ............................................................................................................................ 89Â Figure 4.62. Surface Deflections of Flexible Pavement Structures with and without Geosynthetic ..................................................................................................................... 90Â Figure 4.63. Vertical Stress Distribution within Geosynthetic-Reinforced and Unreinforced Flexible Base Layer .................................................................................... 91Â Figure 4.64. Tensile Bending Stresses at the Bottom of the PCC Slab for the Geosynthetic-Reinforced and Unreinforced Rigid Pavements ......................................... 92Â Figure 4.65. Tensile Stresses at the Top of the PCC Slab for the Geosynthetic-Reinforced and Unreinforced Rigid Pavements .................................................................................. 93Â Figure 4.66. Sensitivity of Model-Predicted Pavement Responses to Subgrade Modulus ........... 95Â Figure 4.67. Sensitivity of Model-Predicted Pavement Responses to Geosynthetic Sheet Stiffness............................................................................................................................. 97Â Figure 4.68. Sensitivity of Model-Predicted Pavement Responses to Thickness of Base Course ............................................................................................................................... 98Â Figure 4.69. Location of Instruments in Flexible Pavement Structures ....................................... 99Â Figure 4.70. Location of Instruments in Rigid Pavement Structures .......................................... 100Â Figure 4.71. Comparison of Measured and Predicted Surface Deflections for Pavement Structures with and without Geosynthetic ...................................................................... 101Â Figure 4.72. Comparison of Measured and Predicted Tensile Strains at the Bottom of Asphalt Layer for Pavement Structures with and without Geosynthetic ........................ 102Â Figure 4.73. Comparison of Measured and Predicted Vertical Stresses within the Base and Subgrade for Pavement Structures with and without Geosynthetic ......................... 103Â Figure 4.74. Comparison of Measured and Predicted Surface Deflections for Rigid Pavement Structures with and without Geosynthetic ..................................................... 104Â Figure 4.75. Comparison of Measured and Predicted Vertical Stresses within the Base and Subgrade for Rigid Pavement Structures with and without Geosynthetic ............... 104Â
ix Figure 4.76. Illustration of Three-Layered Neural Network Architecture .................................. 108Â Figure 4.77. Comparison of Tensile Strain at the Bottom of the Asphalt Layer ........................ 109Â Figure 4.78. Comparison of Average Vertical Strain in the Asphalt Layer ............................... 110Â Figure 4.79. Comparison of Average Vertical Strain in the Base Layer .................................... 111Â Figure 4.80. Comparison of Vertical Strain at the Top of the Subgrade .................................... 112Â Figure 4.81. Comparison of Vertical Strain at 6 inches below the Top of the Subgrade ........... 113Â Figure 4.82. Flowchart of the Process of Predicting Pavement Performance ............................ 115Â Figure 4.83. Geosynthetic-Reinforced Pavement Structures for Case Studies ........................... 116Â Figure 4.84. Effect of Geosynthetic Location and Geosynthetic Type on Fatigue Cracking ..... 118Â Figure 4.85. Effect of Geosynthetic Location and Geosynthetic Type on Rutting Depth .......... 119Â Figure 4.86. Effect of Geosynthetic Location and Geosynthetic Type on IRI ........................... 119Â Figure 4.87. Flowchart of the Process of Validating the Proposed ANN Approach .................. 121Â Figure 4.88. Comparison of Rutting Depth between ANN Approach Prediction and Field Measurement for Pavement Section 16-9032 ................................................................. 122Â Figure 4.89. Comparison of Fatigue Cracking between ANN Approach Prediction and Field Measurement for Pavement Section 16-9032 ........................................................ 123Â Figure 4.90. Comparison of IRI between ANN Approach Prediction and Field Measurement for Pavement Section 16-9032 ................................................................. 123Â Figure 5.1. Measured Horizontal Displacements of Geogrid and UGM When Geogrid Was Placed in the Middle of the Base Course ................................................................ 127Â Figure 5.2. Measured Horizontal Displacements of Geogrid and UGM When Geogrid Was Placed at the Bottom of the Base Course ................................................................ 128Â Figure 5.3. Measured Horizontal Displacements of Geotextile and UGM When Geotextile Was Placed in the Middle of the Base Course .............................................. 128Â Figure 5.4. Measured Horizontal Displacements of Geotextile and UGM When Geotextile Was Placed at the Bottom of the Base Course .............................................. 129Â Figure 5.5. Horizontal and Vertical Moduli of Unreinforced UGM at Each Stress State .......... 130Â Figure 5.6. Effect of Geosynthetics on Horizontal Modulus of UGM ....................................... 130Â Figure 5.7. Effect of Geosynthetics on Vertical Modulus of UGM ............................................ 131Â Figure 5.8. Effect of Geosynthetics on Anisotropic Ratio of UGM ........................................... 131Â Figure 5.9. Effect of Geosynthetic Reinforcement on Reducing Permanent Strain of UGMs .............................................................................................................................. 132Â Figure 5.10. Comparison of Lab-Measured and Proposed-Model-Predicted Permanent Strain Curves for Unreinforced UGMs ........................................................................... 133Â Figure 5.11. Comparison of Lab-Measured and Proposed Model-Predicted Permanent Strain Curves for Geogrid-Reinforced UGMs ................................................................ 133Â Figure 5.12. Comparison of Lab-Measured and Proposed-Model-Predicted Permanent Strain Curves for Geotextile-Reinforced UGMs ............................................................ 134Â Figure 5.13. Effect of Geosynthetic Sheet Stiffness on Predicted Horizontal Modulus of UGM ............................................................................................................................... 135Â Figure 5.14. Effect of Geosynthetic Sheet Stiffness on Predicted Vertical Modulus of UGM ............................................................................................................................... 135Â Figure 5.15. Effect of Base Modulus on Average Compressive Strain in Base Layer ............... 137Â Figure 5.16. Effect of Base Modulus on Compressive Strain at the Top of Subgrade ............... 137Â Figure 5.17. Effect of Subgrade Modulus on Average Compressive Strain in Base Layer ....... 138Â Figure 5.18. Effect of Subgrade Modulus on Compressive Strain at the Top of Subgrade ........ 138Â
x Figure 5.19. Effect of Tensile Sheet Stiffness of Geogrid on Average Compressive Strain in Base Layer .................................................................................................................. 139Â Figure 5.20. Effect of Tensile Sheet Stiffness of Geogrid on Compressive Strain at the Top of Subgrade .............................................................................................................. 139Â Figure 5.21. Effect of Base Modulus on Rutting Depth of Geosynthetic-Reinforced and Unreinforced Pavements ................................................................................................. 140Â Figure 5.22. Effect of Base Modulus on Fatigue Cracking of Geosynthetic-Reinforced and Unreinforced Pavements .......................................................................................... 140Â Figure 5.23. Effect of Base Modulus on IRI of Geosynthetic-Reinforced and Unreinforced Pavements ................................................................................................. 141Â Figure 5.24. Effect of Subgrade Modulus on Rutting Depth of Geosynthetic-Reinforced and Unreinforced Pavements .......................................................................................... 141Â Figure 5.25. Effect of Subgrade Modulus on Fatigue Cracking of Geosynthetic- Reinforced and Unreinforced Pavements ....................................................................... 142Â Figure 5.26. Effect of Subgrade Modulus on IRI of Geosynthetic-Reinforced and Unreinforced Pavements ................................................................................................. 142Â Figure 5.27. Effect of Sheet Stiffness of Geogrid on Rutting Depth of Reinforced Pavements ....................................................................................................................... 143Â Figure 5.28. Effect of Sheet Stiffness of Geogrid on Fatigue Cracking of Reinforced Pavements ....................................................................................................................... 143Â Figure 5.29. Effect of Sheet Stiffness of Geogrid on IRI of Reinforced Pavements .................. 144Â
xi LIST OF TABLES Table 2.1. Summary of Finite Element Model Studies on Geosynthetic-Reinforced Pavements ........................................................................................................................... 7Â Table 2.2. Summary of Design Methods for Pavements with Geosynthetics ................................ 8Â Table 3.1. LST Experiment Design for Flexible Pavement .......................................................... 10Â Table 3.2. LST Experiment Design for Rigid Pavement .............................................................. 10Â Table 3.3. Loading Protocol for Flexible and Rigid Pavement in LST Experiments ................... 10Â Table 4.1. Triaxial Test Protocol for Determining Cross-Anisotropic Properties ........................ 20Â Table 4.2. Influence of Geosynthetic on Material PropertiesâGeosynthetic Location: Mid-Height ........................................................................................................................ 21Â Table 4.3. Influence of Geosynthetic on Material PropertiesâGeosynthetic Location: One-Quarter below the Middle ......................................................................................... 22Â Table 4.4. Influence of Geosynthetic on Material PropertiesâGeosynthetic Location: Bottom............................................................................................................................... 23Â Table 4.5. Proposed Permanent Deformation Test ProtocolâProposed Stress Levels for Calibration of Model Coefficients .................................................................................... 26Â Table 4.6. Proposed Permanent Deformation Test ProtocolâProposed Stress Levels for Validation of Model Coefficients ..................................................................................... 27Â Table 4.7. Determination of Model Coefficients for the UGM with and without Geosynthetics .................................................................................................................... 28Â Table 4.8. General Description of the Instrumentation Plan in LST ............................................ 38Â Table 4.9. Selected Laboratory Tests for Material Characterization ............................................ 81Â Table 4.10. Determined Prony-Series Model Coefficients for the Plant-Mixed, Laboratory-Compacted (PMLC) Asphalt Concrete .......................................................... 82Â Table 4.11. Cross-Anisotropic Properties of the UGM Used in LST Test ................................... 83Â Table 4.12. Comparison of Geosynthetic Sheet Stiffness Values between Laboratory Test and Manufacturerâs Specifications ................................................................................... 85Â Table 4.13. Computed Critical Strains for Geosynthetic-Reinforced and Unreinforced Flexible Pavement Structures ........................................................................................... 92Â Table 4.14. Selected Input Parameters for Geosynthetic-Reinforced Pavement Structures ....... 106Â Table 4.15. Selected Input Parameters for Unreinforced Pavement Structures .......................... 107Â Table 4.16. Material Properties of Geosynthetic-Reinforced Pavements for Case StudiesâMaterial Properties of Control Pavement ........................................................ 117Â Table 4.17. Material Properties of Geosynthetic-Reinforced Pavements for Case StudiesâMaterial Properties for Geosynthetic Products ............................................... 117Â Table 4.18. Determination of Modified Material Properties for Case Studies ........................... 117Â Table 5.1. Summary of Specifics of LST Experiments on Flexible Pavements ......................... 125Â Table 5.2. Summary of Specifics of LST Experiments on Rigid Pavements ............................. 126Â