Experimental Rock Deformation — The Brittle Field

Contents......Page 7
1 Introduction......Page 11
2.1.1 Principle and Terminology......Page 14
2.1.2 Triaxial Testing Apparatus......Page 16
2.1.3 Preparation and Jacketing of Specimens......Page 21
2.1.4 Measurements, Control, and Data Reduction......Page 22
2.2 Other Types of Tests......Page 24
3.1 Introduction......Page 26
3.2 Types of Fractures......Page 27
3.3 Observed Stresses at Brittle Failure......Page 30
3.4 Influence of Strain Rate, Temperature, and Time......Page 36
3.5 Size and Shape Effects......Page 39
3.6 Influence of Intermediate Principal Stress......Page 44
3.7.1 Observations......Page 47
3.7.2 Theoretical Analysis......Page 50
4.1 Introduction......Page 54
4.2 Uniaxial Tension......Page 55
4.3 Uniaxial Compression and Biaxial Stresses......Page 58
4.4 Triaxial Stresses......Page 60
4.5 Modified Griffith Theory (Closed Cracks)......Page 62
4.6.2 Compressive Failure......Page 64
4.7 General Comment on Griffith-Type Theories......Page 65
5.1 Introduction......Page 67
5.2.1 Role of the Testing Machine......Page 68
5.2.2 Complete Force-Displacement Curves......Page 70
5.3 Volume Changes......Page 76
5.4.1 General......Page 84
5.4.2 Background Theory and Observation......Page 85
5.4.3 Stress-Induced Changes in Elastic Wave Speeds......Page 89
5.4.4 Attenuation......Page 95
5.5 Transport Properties......Page 96
5.6 Acoustic Emission......Page 101
5.7.2 Observational Methods......Page 107
5.7.3 Initial Structure......Page 109
5.7.4 Effects of Stressing......Page 113
5.8 A Synoptic View of Brittle Failure......Page 119
6.1 Introduction......Page 123
6.2.1 Initiation of Stress-Induced Microcracking......Page 124
6.2.2 Microcrack Propagation and Stability......Page 127
6.2.3 Microcrack Interaction and Damage Mechanics of Brittle Failure......Page 128
6.2.4 General Comments on Micromechanics-Based Damage Mechanics Models for Compact Rock......Page 135
6.2.5 Stochastic Model of Brittle Failure in Compact Rock......Page 138
6.2.6 Time-Dependent Failure of Compact Rock......Page 141
6.3.2 Strongly Cohesive Porous Rock......Page 142
6.3.3 Weakly Cohesive Porous Rock......Page 143
6.4.1 Application of Plasticity Theory and Bifurcation Analysis......Page 145
6.4.2 Comments on Localization Theory......Page 151
7.1 Introduction......Page 154
7.2 The Notion of Effective Stress......Page 155
7.3.1 Linear Poroelasticity......Page 156
7.3.2 Experimental Measurement of Poroelastic Properties......Page 159
7.4.1 Drained Tests......Page 162
7.4.2 Undrained Tests......Page 165
7.4.3 Chemical Effects......Page 167
7.5 Brittle Failure – Theory of Pore Pressure Effects......Page 168
8.1 Introduction......Page 171
8.2.1 General......Page 172
8.2.2 Influence of Variables......Page 174
8.3.2 Time Dependence of Static Friction......Page 179
8.3.3 Velocity Dependence of Kinetic Friction......Page 182
8.3.4 Rate- and State-Dependent Friction......Page 189
8.3.5 Experimental Observations on the Occurrence of Stick-Slip......Page 194
8.3.6 Influence of Friction Constitutive Behaviour and Machine Stiffness on Stick-Slip......Page 200
8.3.7 Nucleation and Propagation of Dynamic Shear Rupture......Page 202
8.4.1 Frictional Slip, Wear and the Formation of Gouge......Page 204
8.4.2 Gouge Deformation......Page 206
8.4.3 Physical Factors Determining the Frictional Strength......Page 209
8.4.4 Physical Basis for the Direct Effect (Velocity Parameter a)......Page 211
8.4.5 Physical Basis for the Ageing and Evolution Effects (Parameters β and b)......Page 213
9.1 Introduction......Page 216
9.2.1 Role of Confining Pressure......Page 217
9.2.2 Role of Temperature and Strain Rate......Page 222
9.2.3 Physical Properties and Pressure Sensitivity......Page 224
9.2.4 Microstructural Observations......Page 226
9.3.1 Preliminaries......Page 227
9.3.2 Brittle-Ductile Transition with Increasing Pressure......Page 230
9.3.3 Continuum Models and Localization Analysis......Page 233
9.3.4 Influence of Temperature, Strain Rate and Water......Page 237
9.4.1 High Pressure Embrittlement......Page 238
9.4.2 High Temperature Embrittlement......Page 239
A1.1 Stress Intensity Analysis......Page 243
A1.2 Critical Parameters for Failure......Page 246
A1.3 Dynamic and Kinetic Effects......Page 248
A2.1 Introduction......Page 251
A2.2 Constitutive Relations for a Material without Pressure Dependence or Dilatancy......Page 252
A2.3 Constitutive Model for Dilatant, Pressure-Sensitive Materials......Page 254
A2.4 Bifurcation, Instability and Shear Localization......Page 258
A3.1 Introduction......Page 261
A3.2 Friction Law......Page 262
A3.3 Evolution Law......Page 263
A3.4 Time-Dependent Evolution during Stationery Contact......Page 265
A3.5 Analysis of Frictional Stability – Stick-Slip......Page 266
A3.6 Influence of Normal Stress and Temperature......Page 267
References......Page 270
C......Page 337
D......Page 339
F......Page 340
H......Page 342
M......Page 343
P......Page 344
R......Page 345
S......Page 346
T......Page 348
Z......Page 349