Numerical Modelling and Analysis of Fluid Flow and Deformation of Fractured Rock Masses (eBook)

Cover 1
Contents 8
Preface 4
Chapter 1. Introduction to Modelling Deformation and Fluid Flow of Fractured Rock 12
1.1. Introduction 12
1.2. Approaches to modelling rock systems 13
1.3. Continuum models 15
1.4. Flow models 17
1.5. Discontinuum models 19
1.6. Overview of UDEC 20
1.7. Summary of numerical modelling 29
Chapter 2. Modelling of Simple Rock Blocks 34
2.1. Introduction 34
2.2. Basic components of natural fracture networks 34
2.3. Model geometry and initial conditions 36
2.4. Basic behaviour of deformation and fluid flow 36
2.5. Effects of fracture geometry 42
2.6. Effects of fracture properties 49
2.7. Effects of applied boundary stresses 53
2.8. Effects of rock deformation models 55
2.9. Summary 59
Chapter 3. Evaluation of 2-Dimensional Permeability Tensors 64
3.1. Introduction 64
3.2. Calculation of components of flow-rates 65
3.3. Permeability in naturally fractured rocks 70
3.4. Geometrical effects on permeability 74
3.5. Effects of stress on permeability 80
3.6. Conclusions 91
Appendix 3-A 1: Input codes for example one 96
Appendix 3-A2: Derivation of 2-D permeability tensor 98
Chapter 4. Scaling of 2-D Permeability Tensors 102
4.1. Introduction 102
4.2. Development of the previous approach 103
4.3. Testing the concept of a representative element volume by down-scaling 105
4.4. Scaling-up of permeability 110
4.5. Effects of sample number and sample size 114
4.6. Determining the permeability of a region 119
4.7. Conclusions 123
Chapter 5. Percolation Behaviour of Fracture Networks 124
5.1. Introduction 124
5.2. Modelling of 2-dimensional fracture networks 124
5.3. Density, percolation threshold and fractal dimension 125
5.4. Critical behaviour of fractured rock masses 129
5.5. Conclusions 139
Chapter 6. Slip and Fluid Flow around An Extensional Fault 142
6.1. Introduction 142
6.2. Outline of modelling 142
6.3. Stress distribution and fluid flow in model A: At a shallow depth with a hydrostatic fluid pressure 147
6.4. Comparison of model A with a supra-hydrostatic fluid pressure at greater depth 154
6.5. Effects of irregularities in fault zone 158
6.6. Discussion of dynamic response of fluid-dilation interactions 161
6.7. Conclusions 163
Chapter 7. Instability and Associated Localization of Deformation and Fluid Flow in Fractured Rocks 166
7.1. Introduction 166
7.2. Numerical determination of instability 167
7.3. Instability and R-ratio 170
7.4. Effects of fracture network geometry 176
7.5. Multifractal description of flow localisation 185
7.6. Permeability of three natural fracture networks before and at critical stress state 189
7.7. Effects of loading direction 192
7.8. Is the crust in a critical state? 194
7.9. Implications for mineral deposits 194
7.10. Conclusions 196
Chapter 8. Grain Scale Flow of Fluid in Fractured Rocks 198
8.1. Introduction 198
8.2. Simulation of Deformation and Fracturing in Matrix Models 199
8.3. Dual Permeability Model 200
8.4. Results 201
8.5. Discussion and Conclusions 219
Chapter 9. Changes of Permeability due to Excavation of Ship-Locks of the Three Gorges Project, China 222
9.1. Introduction 222
9.2. Estimation of permeability 225
9.3. Permeability before excavation 227
9.4. Modelling of the excavation of the ship-locks 234
9.5. Permeability after excavation 236
9.6. Concluding discussion 241
Chapter 10. Wellbore Instability due to "Block Loosening" in Fractured Rock Masses 244
10.1. Introduction 244
10.2. Model geometry and conditions used 245
10.3. Randomly isotropic fracture geometry with constant wellbore pressure 247
10.4. Randomly isotropic fracture geometry with increased or reduced wellbore pressure 257
10.5. Comparison of different fracture patterns 257
10.6. Conclusions 262
Appendix 10-A1: Analytic solution for a homogeneous medium 265
Summary 266
References 272
Index 288