Preface
The scale effect objectively exists. The scale effect of rock refers to the dependence of the change of the rock’s mechanical properties on the size of the sampling grid. The scale is the spatial dimension and time dimension of the object or process. The spatial scale refers to the area size of the study unit or the spatial resolution level of the smallest information unit, and the time scale is the time interval of its dynamic change. There are great mechanical differences in the strength and deformation characteristics of rocks of different sizes. The strength and deformation characteristics of rocks of a certain size cannot be directly applied to geotechnical engineering design and the establishment of constitutive relations. Therefore, rock scale analysis and scale effect are important to the engineering.
Rock mass differs from the general continuous medium in that there are various structural planes in the rock mass. Also, the rock mass structure, composed of the structural plane and the rock created by the structural plane, control the mechanics and mechanical properties of the rock mass. The influence of the rock mass structure on the mechanical properties of the rock mass is called the structural effect of rock mass mechanical properties. Due to the loading and unloading processes of engineering loads, structural loads, temperature loads, and underground fluid infiltration, the stability of rock engineering is a very prominent area of research. It has become a research hotspot of geotechnical engineering to study the structural effects of rock mass.
This book summarizes and enriches the latest research results on the scalesize and structural effects of rock materials, including test methods, innovative technologies and their applications in indoor tests, rock mechanics, and rock engineering. The book is divided into five chapters: Chapter 1: Size Effect of Rock Samples (Hossein Masoumi); Chapter 2: Rock Fracture Toughness (Sheng Zhang); Chapter 3: Scale Effect of Rock Joint (Joung Oh); Chapter 4: Microseismic Monitoring and Application (Shuren Wang 1–3, Xiangxin Liu 4–6), and Chapter 5: Structural Effect of Rock Blocks (Shuren Wang 1–6, Wenbing Guo 7). This book is innovative, practical, and rich in content. It will be of great use and interest to researchers undertaking various rock tests, geotechnical engineering, and rock mechanics as well as for teachers and students in related universities and onsite technical people.
The material presented in this book contributes to the expansion of knowledge related to rock mechanics and engineering. Through their extensive fundamental and applied research over the past decade, the authors cover a diverse range of topics, including the scale-size and structural effects of rock materials through the interaction of large-scale rock masses and engineering practices; the mechanics of rock cutting; techniques to improve the strength and integrity of rock structures in surface and underground excavations; and improvements in approaches to modeling techniques used in engineering design.
Contents:
Chapter 1
Size effect of rock samples
Hossein Masoumi
Department of Civil Engineering, Faculty of Engineering, Monash University, Melbourne,
VIC, Australia
Chapter outline
1.1 Size effect law for intact rock 2
1.1.1 Introduction 2
1.1.2 Background 3
1.1.3 Experimental study 9
1.1.4 Unified size effect law 19
1.1.5 Reverse size effects in UCS results 24
1.1.6 Contact area in size effects of point load results 28
1.1.7 Conclusions 34
1.2 Length-to-diameter ratio on point load strength index 35
1.2.1 Introduction 35
1.2.2 Background 36
1.2.3 Methodology 38
1.2.4 Valid and invalid failure modes 39
1.2.5 Conventional point load strength index size effect 42
1.2.6 Size effect of point load strength index 44
1.2.7 Conclusions 49
1.3 Plasticity model for sizedependent behavior 51
1.3.1 Introduction 51
1.3.2 Notation and unified size effect law 53
1.3.3 Bounding surface plasticity 55
1.3.4 Model ingredients 57
1.3.5 Model calibration 65
1.3.6 Conclusions 74
1.4 Scale-size dependency of intact rock 77
1.4.1 Introduction 77
1.4.2 Rock types 78
1.4.3 Experimental procedure 80
1.4.4 Comparative study 91
1.4.5 Conclusion 103
1.5 Scale effect into multiaxial failure criterion 103
1.5.1 Introduction 103
1.5.2 Background 106
1.5.3 Scale and Weibull statistics into strength measurements 107
1.5.4 The modified failure criteria 111
1.5.5 Comparison with experimental data 117
1.5.6 Conclusions 121
1.6 Size-dependent Hoek-Brown failure criterion 121
1.6.1 Introduction 121
1.6.2 Background 122
1.6.3 Size-dependent Hoek- Brown failure criterion 126
1.6.4 Example of application 136
1.6.5 Conclusions 137
References 137
Further reading 144
Chapter 2
Rock fracture toughness
Sheng Zhang
School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, China
Chapter outline
2.1 Fracture toughness of splitting
disc specimens 146
2.1.1 Introduction 146
2.1.2 Preparation of disc
specimens 147
2.1.3 Fracture toughness of five
types of specimens 148
2.1.4 Load-displacement curve
of disc splitting test 153
2.1.5 Comparison of disc
splitting test results 155
2.1.6 Conclusions 158
2.2 Fracture toughness of HCFBD 159
2.2.1 Introduction 159
2.2.2 Test method
and principle 160
2.2.3 HCFBD specimens with
prefabricated cracks 162
2.2.4 Calibration of maximum
dimensionless SIF Ymax 163
2.2.5 Results and analysis 164
2.2.6 Conclusions 168
2.3 Crack length on dynamic
fracture toughness 169
2.3.1 Introduction 169
2.3.2 Dynamic impact
splitting test 169
2.3.3 Results and discussion 171
2.3.4 DFT irrespective of
configuration and size 175
2.3.5 Conclusions 176
2.4 Crack width on fracture
toughness 177
2.4.1 Introduction 177
2.4.2 NSCB three-point
flexural test 178
2.4.3 Width influence on
prefabricated crack 180
2.4.4 Width influence of
cracks on tested fracture
toughness 183
2.4.5 Method for eliminating
influence of crack width 185
2.4.6 Conclusions 187
2.5 Loading rate effect of
fracture toughness 188
2.5.1 Introduction 188
2.5.2 Specimen preparation 189
2.5.3 Test process and data
processing 189
2.5.4 Results and analysis 191
2.5.5 Conclusions 204
2.6 Hole influence on dynamic
fracture toughness 204
2.6.1 Introduction 204
2.6.2 Dynamic cleaving
specimens and
equipment 205
2.6.3 SHPB test and data
record 207
2.6.4 Dynamic finite element
analysis 210
2.6.5 Results analysis and
discussion 212
2.6.6 Conclusions 217
2.7 Dynamic fracture toughness
of holed-cracked discs 217
2.7.1 Introduction 217
2.7.2 Dynamic fracture
toughness test 219
2.7.3 Experimental recordings
and results 221
2.7.4 Dynamic stress
intensity factor in
spatial-temporal
domain 226
2.7.5 Conclusions 253
2.8 Dynamic fracture propagation
toughness of P-CCNBD 231
2.8.1 Introduction 231
2.8.2 Experimental
preparation 233
2.8.3 Experimental recording
and data processing 237
2.8.4 Numerical calculation
of dynamic stress
intensity factor 242
2.8.5 Determine dynamic
fracture toughness 247
2.8.6 Conclusions 253
References 254
Further reading 258
Chapter 3
Scale effect of the rock joint
Joung Oh
School of Minerals and Energy Resources Engineering, The University of New South Wales, Sydney,
NSW, Australia
Chapter outline
3.1 Fractal scale effect of
opened joints 260
3.1.1 Introduction 260
3.1.2 Scale effect based on
fractal method 262
3.1.3 Constitutive model for
opened rock joints 266
3.1.4 Validation of proposed
scaling relationships 268
3.1.5 Conclusions 272
3.2 Joint constitutive model
for multiscale asperity
degradation 274
3.2.1 Introduction 274
3.2.2 Quantification of
irregular joint profile 275
3.2.3 Description of proposed
model 277
3.2.4 Joint model validation 281
3.2.5 Conclusions 288
3.3 Shear model incorporating
small- and large-scale
irregularities 290
3.3.1 Introduction 290
3.3.2 Constitutive model for
small-scale joints 291
3.3.3 Constitutive model for
large-scale joints 294
3.3.4 Correlation with
experimental data 299
3.3.5 Conclusions 308
3.4 Opening effect on joint shear
behavior 309
3.4.1 Introduction 309
3.4.2 Constitutive model for
joint opening effect 310
3.4.3 Opening model
performance 312
3.4.4 Discussion 317
3.4.5 Conclusions 318
3.5 Dilation of saw-toothed
rock joint 318
3.5.1 Introduction 318
3.5.2 Constitutive law for
contacts in DEM 320
3.5.3 Model calibration 320
3.5.4 Direct shear test simulation 323
3.5.5 Conclusions 333
3.6 Joint mechanical behavior
with opening values 334
3.6.1 Introduction 334
3.6.2 Normal deformation
of opened joints 337
3.6.3 Direct shear tests 350
3.6.4 Results analysis and
discussion 351
3.6.5 Conclusions 356
3.7 Joint constitutive model
correlation with field
observations 357
3.7.1 Introduction 357
3.7.2 Model description and
implementation 358
3.7.3 Stability analysis of largescale
rock structures 365
3.7.4 Conclusions 385
References 390
Further reading 397
Chapter 4
Microseismic monitoring and
application
Shuren Wanga and Xiangxin Liub
aSchool of Civil Engineering, Henan Polytechnic University, Jiaozuo, China, bSchool of Mining
Engineering, North China University of Science and Technology, Tangshan, China
Chapter outline
4.1 Acoustic emission of rock plate
instability 400
4.1.1 Introduction 400
4.1.2 Materials and methods 401
4.1.3 Results analysis 405
4.1.4 Discussion of the
magnitudes of AE events 407
4.1.5 Conclusions 408
4.2 Prediction method of rockburst 409
4.2.1 Introduction 409
4.2.2 Microseismic monitoring
system 410
4.2.3 Active microseismicity
and faults 412
4.2.4 Rockburst prediction
indicators 415
4.2.5 Conclusions 420
4.3 Near-fault mining-induced
microseismic 420
4.3.1 Introduction 420
4.3.2 Engineering situations 422
4.3.3 Computational model 424
4.3.4 Result analysis and
discussion 425
4.3.5 Conclusions 430
4.4 Acoustic emission recognition
of different rocks 432
4.4.1 Introduction 432
4.4.2 Experiment preparation
and methods 434
4.4.3 Results and discussion 439
4.4.4 AE signal recognition
using ANN 442
4.4.5 Conclusions 448
4.5 Acoustic emission in tunnels 448
4.5.1 Introduction 448
4.5.2 Rockburst experiments
in a tunnel 450
4.5.3 Experimental results 453
4.5.4 AE characteristics
of rockburst 458
4.5.5 Discussion 461
4.5.6 Conclusions 466
4.6 AE and infrared monitoring in
tunnels 466
4.6.1 Introduction 466
4.6.2 Simulating rockbursts in
a tunnel 468
4.6.3 Experimental results 471
4.6.4 Rockburst characteristics
in tunnels 482
4.6.5 Conclusions 485
References 486
Further reading 493
Chapter 5
Structural effect of rock blocks
Shuren Wanga and Wenbing Guob
aSchool of Civil Engineering, Henan Polytechnic University, Jiaozuo, China, bSchool of Energy
Science and Engineering, Henan Polytechnic University, Jiaozuo, China
Chapter outline
5.1 Cracked roof rock beams 496
5.1.1 Introduction 496
5.1.2 Mechanical model of a cracked roof beam 497
5.1.3 Instability feature of cracked roof beams 505
5.1.4 Mechanical analysis of roof rock beams 507
5.1.5 Conclusions 512
5.2 Evolution characteristics of fractured strata structures 512
5.2.1 Introduction 512
5.2.2 Engineering background 515
5.2.3 Mechanical and computational model 517
5.2.4 Results and discussion 521
5.2.5 Conclusions 531
5.3 Pressure arching characteristics in roof blocks 532
5.3.1 Introduction 532
5.3.2 Pressure arching characteristics 534
5.3.3 Evolution characteristics of pressure arch 541
5.3.4 Results and discussion 546
5.3.5 Conclusions 549
5.4 Composite pressure arch in thin bedrock 550
5.4.1 Introduction 550
5.4.2 Engineering background and pressure arch structure 551
5.4.3 Computational model and similar experiment 557
5.4.4 Results and discussion 560
5.4.5 Conclusions 568
5.5 Pressure arch performances in thick bedrock 569
5.5.1 Introduction 569
5.5.2 Engineering background 571
5.5.3 Pressure-arch analysis and experimental methods 572
5.5.4 Results and discussion 577
5.5.5 Conclusions 586
5.6 Elastic energy of pressure arch evolution 587
5.6.1 Introduction 587
5.6.2 Engineering background 589
5.6.3 Pressure-arch analysis and computational model 591
5.6.4 Simulation results and discussion 594
5.6.5 Conclusions 604
5.7 Height predicting of waterconducting zone 605
5.7.1 Introduction 605
5.7.2 High-intensity mining in china 606
5.7.3 Oft influence on FWCZ development 608
5.7.4 Development mechanism of FWCZ based on OFT 611
5.7.5 Example analysis and numerical simulation 613
5.7.6 Engineering analogy 624
5.7.7 Conclusions 627
References 627
Further reading 633