Experimental Unsaturated Soil Mechanics (eBook)

Foreword 6
Contents 8
Part I Microstructure and Fabric 13
Influence of Relative Density and Clay Fraction on Soils Collapse 14
1 Introduction 14
2 Materials, Equipment and Testing Procedure 15
3 Results and Discussion 17
4 Conclusions 20
References 20
Microstructure Features in the Behaviour of Engineered Barriers for Nuclear Waste Disposal 21
1 Introduction 21
2 The Microstructure of Compacted Soils 22
3 Effect of Changes in Water Content 30
4 Hydration Mechanisms in Smectites 32
5 Application to Compacted Bentonites 36
6 Concluding Remarks 39
References 40
Microstructure of Gypsiferous Crust and Its Importance to Unsaturated Soil Behaviour 43
Introduction 43
Materials and Methods 44
Results and Discussion 45
Conclusions 49
References 49
Fabric Changes in Compacted London Clay Due to Variations in Applied Stress and Suction 51
Introduction 51
Materials and Methods 52
Results 53
Discussion and Conclusions 56
Acknowledgements 57
References 57
Microstructure of a Lime Stabilised Compacted Silt 59
1 Introduction 59
2 Experimental Procedures 60
3 Results 61
4 Conclusions 65
References 66
Part II Measuring Suction 67
Errors in Total Suction Measurements 68
Introduction 68
Total Suction Measurement Techniques 70
Total Suction Measurement Errors 71
Effects of Total Suction Measurement Errors 76
Conclusions 78
References 78
Application of a Dew Point Method to Obtain the Soil Water Characteristic 80
Introduction 80
The Dew Point Method 81
Performance Verification 82
Sample Preparation 83
Results 84
Conclusions 86
References 86
A Comparative Study of Soil Suction Measurement Using Two Different High- Range Psychrometers 87
1 Introduction 87
2 Equipment Used for Total Suction Measurement 88
3 Calibration Protocols 91
4 Water Retention Curves 95
5 Conclusions 99
Acknowledgements 100
References 100
Determination of the Soil Water Retention Curve with Tensiometers 102
Introduction 102
1 Experimental Set up 103
2 Results 105
Discussion 106
Conclusions 108
References 109
Tensiometer Development for High Suction Analysis in Laboratory Lysimeters 110
1 Introduction 111
2 Description of the Equipment – Tensiometer 116
3 Results 119
4 Final Comments 120
Acknowledgements 121
References 121
Part III Strength and Dilatancy 123
Dilatancy of Coarse Granular Aggregates 124
Background 124
Suction Controlled Triaxial Tests on Hard Limestone Gravel 129
Dilatancy 132
Summary and Conclusions 138
Acknowledgements 139
References 139
A Laboratory Investigation into the Effect of Water Content on the CBR of a Subgrade soil 141
Introduction 141
Methodology 142
Discussion of Results 143
Conclusion 147
References 147
Shear Strength Affected by Suction Tension in Unsaturated Fine Grained Soils? 149
1 Expected Effects of Suction on Strength 149
2 Characterisation of the Tested Materials 151
3 Suction Measurements Results 152
4 Shear Test Results 153
5 Conclusions 156
References 156
Shear Strength Behaviour of Unsaturated Silty Soil 157
1 Introduction 157
2 Test Procedure and Program 158
3 Results and Discussion 159
4 Conclusion 163
References 163
Experimental Investigation on the Time Dependent Behaviour of a Multiphase Chalk 164
Introduction 164
Tested Material and Experimental Techniques 165
Void Ratio–Time Relationship 165
Stress-Void Ratio Relationship 167
Creep Evolution 168
Conclusion 169
Acknowledgements 169
References 169
Testing Unsaturated Soil for Plane Strain Conditions: A New Double Wall Biaxial Device 171
Introduction 171
The New Biaxial Double Wall Cell 172
Calibration 174
Conclusions 178
Acknowledgements 178
References 178
Influence of State Variables on the Shear Behaviour of an Unsaturated Clay 181
1 Introduction 181
2 Triaxial Tests 182
3 Constitutive Relation 183
4 Conclusions 185
Acknowledgment 185
References 185
Effect of Capillary and Cemented Bonds on the Strength of Unsaturated Sands 187
1 Introduction 187
2 Experiments: Preparation of the Samples and Protocol of Test 188
3 Results and Discussions 189
4 Numerical Approach 193
5 Conclusion 194
References 194
Determining the Shear Strength of Unsaturated Silt 196
Introduction 196
Modified Direct Shear Testing Device 198
Procedures 199
Testing Experiment 200
Summary and Conclusions 205
Acknowledgments 206
References 206
Factors Affecting Tensile Strength Measurement and Modified Tensile Strength Measuring Apparatus for Soil 208
Introduction 208
Test Apparatus 209
Materials and Specimen Preparation 210
Test Conditions 213
Results and Discussions 214
Conclusions 218
Acknowledgements 219
References 219
The Tensile Strength of Compacted Clays as Affected by Suction and Soil Structure 220
Introduction 220
Soil Structure 221
Test Procedure and Soil Characteristics 222
Test Results 225
Conclusions 226
References 226
Part IV Temperature Effects 228
Modified Isochoric Cell for Temperature Controlled Swelling Pressure Tests 229
Introduction 229
Equipment and Verification 230
Material Used 232
Swelling Pressure Measurement 233
Result and Discussion 235
Conclusion 239
Acknowledgment 240
References 240
Some Aspects of the Effect of the Temperature on the Behaviour of Unsaturated Sandy Clay 242
1 Introduction 242
2 Materials and Experimental Devices 243
3 Results and discussion 245
4 Conclusion 248
References 249
Influence of Temperature on the Water Retention Curve of Soils. Modelling and Experiments 250
1 Introduction 250
2 Constitutive Thermo-Hydraulic Model 251
3 Experimenal Validation 253
4 Conclusion 257
References 257
Thermo-Hydro-Mechanical Behaviour of Compacted Bentonite 258
1 Introduction 258
2 Materials and Methods 259
3 Test Results 261
4 Conclusion 263
References 264
Retention Curves of Two Bentonites at High Temperature 265
1 Introduction 265
2 Material 266
3 Methodology 266
4 Results 267
5 Summary 270
References 271
Part V Volumetric Behaviour – Expansive Materials 273
Experimental Study on Shrinkage Behaviour and Prediction of Shrinkage Magnitudes of Residual Soils 274
Introduction 274
Materials and Methods 275
Results and Discussion 276
Conclusions 280
References 280
Assessment of Swelling Deformation of Unsaturated Kaolinite Clay 282
1 Introduction 282
2 Constitutive Relation for Volume Change 283
3 Test Material, Equipment, and Procedure 283
4 Test Results 284
5 Numerical Simulations 285
6 Conclusions 288
Acknowledgements 288
References 288
Suction and Collapse of Lumpy Spoilheaps in Northwestern Bohemia 289
1 Introduction 289
2 Structure of the Spoilheap Soil 289
3 Field Suction Measurement 291
4 Collapse Potential 292
5 Conclusions 295
References 296
Oedometer Creep Tests of a Partially Saturated Kaolinite Clay 297
1 Introduction 297
2 Test Material 298
3 Test Equipment and Test Procedure 298
4 Test Results 300
5 Conclusions 302
References 303
Analysis of the Expansive Clay Hydration under Low Hydraulic Gradient 304
1 Introduction 304
2 Basic THM Formulation 305
3 Infiltration Tests 307
4 Numerical Modelling 308
5 Conclusions 312
References 312
Moisture Effects on Argillaceous Rocks 314
Introduction 314
Studied Materials 315
Water Retention 315
Swelling Pressure 316
Swelling and Shrinking Strains 317
Self-Sealing 319
Conclusions 320
Acknowledgements 321
References 321
Part VI Retention Behaviour 322
Results from Suction Controlled Laboratory Tests on Unsaturated Bentonite – Verification of a Model 323
1 Background 323
2 Material and Test Methods 324
3 Results 325
4 Analysis 327
5 Conclusions 328
Acknowledgement 329
References 329
Variation of Degree of Saturation in Unsaturated Silty Soil 330
1 Introduction 330
2 Experimental Study 331
3 Results and Discussion 332
4 Conclusion 335
References 335
Mechanical Behaviour of Compacted Scaly Clay During Cyclic Controlled- Suction Testing 337
Introduction 337
Experimental Programme 338
Test Results and Interpretation 340
Conclusions 345
References 345
Prediction of Soil–Water Characteristic Curve Based on Soil Index Properties 347
1 Introduction 347
2 Definitions 349
3 Methods of Obtaining SWCC 350
4 Proposed Model for Predicting the SWCC 352
5 Comparison 353
6 Conclusions 356
Acknowledgements 358
References 358
Water Balance and Effectiveness of Mineral Landfill Covers – Results of Large Lysimeter Test- Fields 360
Introduction 360
Materials and Methods 361
Data Collection 362
Results and Discussion 363
Conclusions 365
References 367
A Retention Curve Prediction for Unsaturated Clay Soils 368
1 Introduction 368
2 Test Program, Results and Analysis 372
3 Prediction of the Experimental Results 374
4 Conclusion 376
References 376
Unsaturated-Zone Leaching and Saturated- Zone Mixing Model in Heterogeneous Layers 378
1 Introduction 378
2 Governing Equation and Boundary and Initial Conditions 379
3 Numerical Implementation 383
4 Program Execution 385
5 Summary 388
References 390
Prediction of SWCC for Coarse Soils Considering Pore Size Changes 391
Introduction 391
Materials 392
Experimental Methods 394
Results and Discussions 396
Summary and Conclusions 401
Acknowledgements 402
References 402
The Influence of the Pore Fluid on Desiccation of a Deformable Porous Material 403
Introduction 403
Desiccation Tests 404
Discussion 406
Conclusions and Open Issues 409
Acknowledgment 409
References 409
Determination of the Soil Water Retention Curve and the Unsaturated Hydraulic Conductivity from the Particle Size Distribution 411
1 Introduction 411
2 Calculation of the Pore Constriction Distribution 412
3 Derivation of Soil Hydraulic Parameters 415
4 Summary and Conclusion 420
References 422
Part VII Field Applications 424
Earthquake-Induced Mudflow Mechanism from a Viewpoint of Unsaturated Soil Dynamics 425
1 Introduction 425
2 Cyclic Triaxial Test for Unsaturated Sandy Soils 427
3 Test Results and Discussion 429
4 Conclusions 432
References 432
Plate-Load Tests on an Unsaturated Lean Clay 433
Introduction 433
Previous Studies 434
Site Characterization 434
Field Experimental Program 434
Results and Discussion 436
Conclusions 439
References 440
Selfsealing Barriers of Clay/Mineral Mixtures. The SB Project at the Mont Terri Rock Laboratory 441
1 Introduction 441
2 Laboratory Characterization of Moderately Compacted Clay/ Sand- Mixtures 442
3 In-Situ and Full-Scale Mockup Experiments 444
4 Conclusions 447
Acknowledgements 448
References 448
Preferential Water Movement in Homogeneous Soils 449
1 Introduction 449
2 Observations on the Full-Scale Dyke Model 450
3 Laboratory Investigations 457
4 Analysis of Experimental Investigations 458
5 Summary and Conclusion 460
References 460
Compaction Properties of Agricultural Soils 462
Introduction 462
Materials and Methods 463
Experimental Results 464
Discussions 467
Conclusions 468
Acknowledgements 468
References 468
Bearing Capacity of Model Footings in Unsaturated Soils 470
Introduction 470
Test Equipment 471
Properties of the Tested Soil 471
Typical Experimental Results 472
The Measured and the Predicted SWRC 473
Bearing Capacity of Unsaturated Soils 475
Comparison between the Measured and Predicted Bearing Capacity of Unsaturated Soils 477
Conclusions 478
Acknowledgements 479
References 479
Influence of Soil Suction on Trench Stability 481
1 Introduction 481
2 Geotechnical Context 482
3 Test Trench Experiment 484
4 Conclusions 486
References 487
Index 488