Geomechanical Behaviors of Bimrocks

425 Pages·2021·29.496 MB·English

by  Wang Yu

Geomechanical Behaviors of
Bimrocks

Geomechanical Behaviors of
Bimrocks

Wang Yu
UNIVERSITY OF SCIENCE AND TECHNOLOGY, BEIJING, P.R. CHINA
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Library of Congress Cataloging-in-Publication Data
Names: Yu, Wang, 1982– author.
Title: Geomechanical behaviors of bimrocks / Wang Yu, University of
Science and Technology, Beijing, P.R. China.
Description: Boca Raton : CRC Press, [2021] | Includes bibliographical
references and index.
Subjects: LCSH: Block theory (Rock mechanics) | Schists. | Soil
mechanics. | Conglomerate.
Classification: LCC TA706 .Y98 2021 (print) | LCC TA706 (ebook) |
DDC 624.1/5132—dc23
LC record available at https://lccn.loc.gov/2020050003
LC ebook record available at https://lccn.loc.gov/2020050004
Published by: CRC Press/Balkema
Schipholweg 107C, 2316 XC Leiden, The Netherlands
e-mail: [email protected]
www.crcpress.com – www.taylorandfrancis.com
ISBN: 978-0-367-72595-2 (hbk)
ISBN: 978-0-367-72596-9 (pbk)
ISBN: 978-1-003-15547-8 (ebk)
DOI: 10.1201/9781003155478
DOI: https://doi.org/10.1201/9781003155478
Contents
About the author xiii
Notations xv
Preface xvii
1 Macro–meso geomechanical behaviors of bimrocks 1
1.1 M echanical behaviors revealed by variable-angle shear experiments 1
1.1.1 Introduction 1
1.1.2 Material description and sample preparation 3
1.1.3 Brief description of the loading system 5
1.1.4 Research idea 6
1.1.5 Results and discussions 8
1.1.5.1 Typical shear force–displacement curve 8
1.1.5.2 Effect of the block size on shear behavior 9
1.1.5.3 Morphology of shear fracture surface 10
1.1.5.4 Strength parameter analysis 12
1.1.5.5 Discussions 14
1.1.6 Conclusions 15
1.2 Macro–meso failure mechanism of bimrock at medium strain rates 16
1.2.1 Introduction 16
1.2.2 Specimen preparation and testing method 17
1.2.2.1 The testing material 17
1.2.2.2 Remolded specimen preparation 19
1.2.2.3 Experimental system 20
1.2.3 Typical stress–strain curve of SRM 21
1.2.4 Elastic moduli analysis 21
1.2.5 Characteristic stress analysis 23
1.2.6 Strain rate dependency analysis 25
1.2.7 Failure mechanism 28
1.2.8 Failure mechanism 30
1.2.9 Conclusions 31
References 32
vi Contents
2 Ultrasonic and mechanical characteristics of bimrocks 36
2.1 Real-time ultrasonic detection of bimrock under uniaxial deformation 36
2.1.1 Introduction 36
2.1.2 Principle of ultrasonic test 37
2.1.3 Experimental procedure 38
2.1.3.1 The testing material 38
2.1.3.2 Remolded specimen preparation 40
2.1.3.3 Experimental system 42
2.1.3.4 Testing procedure 43
2.1.4 The UPV and AC characteristics before loading 46
2.1.5 UCS against rock percentage 47
2.1.6 Failure mechanism 48
2.1.7 Ultrasonic pulse velocity 49
2.1.8 Transmission ratio 50
2.1.9 Relationship between UCS and UPV 52
2.1.10 Comparison of cracking behaviors of bimrocks with those
of soil and rock material 53
2.1.11 Conclusions 54
2.2 Cracking damage evolution of bimrock under real-time ultrasonic testing 56
2.2.1 Introduction 56
2.2.2 Experimental procedure 57
2.2.2.1 The testing material 57
2.2.2.2 Specimen preparation 58
2.2.2.3 Experimental system 59
2.2.2.4 Testing procedure 60
2.2.2.5 Research idea 61
2.2.3 Peak strength variation against rock percentage 63
2.2.4 Failure mechanism 64
2.2.5 Ultrasonic pulse velocity 65
2.2.6 Cracking evolution analysis 65
2.2.7 Damage Constitutive Model 68
2.2.8 Conclusions 74
2.3 Real-time ultrasonic testing for air-dried bimrock under triaxial
deformation 74
2.3.1 Introduction 74
2.3.2 Materials and specimen preparation 75
2.3.3 Test system and procedure 76
2.3.4 Axial stress–strain–UPV curves 77
2.3.5 Stress–UPV dependency analysis 78
2.3.6 Shear strength characteristics 79
2.3.7 Ultimate failure mode analysis 80
2.3.8 Conclusion 80
2.4 Triaxial deformation characteristics of wet bimrock revealed using
the real-time ultrasonic detection 82
2.4.1 Introduction 82
2.4.2 Samples and testing procedure 84
Contents vii
2.4.2.1 Characteristics of materials used in bimsoil 84
2.4.2.2 Sample preparation 84
2.4.2.3 Testing system 86
2.4.2.4 Testing procedure 87
2.4.3 Triaxial stress–strain responses 87
2.4.4 UPV analysis during deformation 87
2.4.5 Analysis of dependency of velocity to stress 92
2.4.6 Correlation between RBP and strength parameters 92
2.4.7 Analysis of failure mechanisms 95
2.4.8 Conclusions 96
2.5 I nvestigation on fracture evolution for bimrock under splitting loads 98
2.5.1 Introduction 98
2.5.2 Experimental methods 99
2.5.2.1 Materials and specimen preparation 99
2.5.2.2 Brief description of the testing system 101
2.5.2.3 Research idea 102
2.5.3 Typical splitting stress–displacement curves 104
2.5.4 Typical stress–displacement–UPV curve 105
2.5.5 Stress–UPV dependency analysis 106
2.5.6 Fracturing evolution analysis 108
2.5.7 Fracture morphology analysis 109
2.5.8 Post-Test 3-D laser scanning analysis 110
2.5.9 Conclusions 112
References 113
3 Static fracture evolution of bimrock revealed by in situ CT  technique 118
3.1 Meso-damage cracking characteristics of bimrock by CT scanning 118
3.1.1 Introduction 118
3.1.2 Experimental procedures 120
3.1.2.1 Physical principles of X-Ray tomography 120
3.1.2.2 Experimental system 121
3.1.2.3 Specimen preparation 121
3.1.2.4 Research idea 123
3.1.2.5 Testing procedure 124
3.1.3 Calibration of rock percentage 125
3.1.4 Meso-damage cracking analysis 125
3.1.5 ROI_CT value characteristics 127
3.1.6 Porosity evolution analysis 128
3.1.7 Damage constitutive model 129
3.1.8 Crack statistical characteristics 132
3.1.9 Conclusions 136
3.2 I n situ CT investigation on meso-structural changes in bimrocks
under uniaxial deformation 136
3.2.1 Introduction 136
3.2.2 Experimental materials and methods 137
3.2.2.1 Tested material, sampling, and preparation 137
viii Contents
3.2.2.2 Experimental apparatus 139
3.2.2.3 Experimental procedure 140
3.2.3 Uniaxial test and CT scanning 141
3.2.4 Identification and extraction of cracks 141
3.2.5 Crack geometry characteristics analysis 144
3.2.6 Damage evolution model 149
3.2.7 Conclusions 149
3.3 Meso-structural changes in bimsoil under triaxial compression 151
3.3.1 Introduction 151
3.3.2 Experimental materials and methods 153
3.3.3 In situ triaxial compression test 154
3.3.3.1 Imaging process method 156
3.3.4 General observations of bimsoil damage and fracture evolution 158
3.3.5 Meso-structural identification and extraction 158
3.3.6 D Meso-structural evolution analysis 158
3.3.7 Localized deformation analysis 163
3.3.7.1 Nonhomogeneity analysis of deformed sample 166
3.3.8 Dilatation behavior analysis 166
3.3.9 Failure morphological analysis 168
3.3.10 Conclusions 169
3.4 Effects of rock blocks on meso-structural changes in bimrock 170
3.4.1 Introduction 170
3.4.2 Materials and methods 173
3.4.2.1 The tested material, sampling, and preparation 173
3.4.2.2 X-ray CT apparatus 174
3.4.2.3 Triaxial loading device 175
3.4.2.4 Testing program 176
3.4.2.5 Image analysis 178
3.4.3 General observations 179
3.4.4 Meso-structural evolution analysis 182
3.4.5 Dilatation behavior analysis 185
3.4.6 Failure morphology analysis 188
3.4.7 Conclusions and outlook 188
3.5 Effects of confining pressure on meso-structural changes in bimrock 190
3.5.1 Introduction 190
3.5.2 Materials and methods 191
3.5.2.1 Tested material and sample preparation 191
3.5.2.2 X-ray CT apparatus 193
3.5.2.3 Triaxial loading device 193
3.5.2.4 Testing procedure for triaxial test 193
3.5.2.5 Image analysis 194
3.5.3 Testing program during in situ CT scanning 196
3.5.4 General observations 197
3.5.5 Meso-structural evolution analysis 199
3.5.6 Dilatation behavior analysis 200
3.5.7 Conclusions 204
References 206
Contents ix
4 Dynamic behavior characterization of bimrocks using the CT technique 211
4.1 Dynamic behavior of bimrock under cyclic triaxial test 211
4.1.1 Introduction 211
4.1.2 Materials 213
4.1.3 Experimental methods 215
4.1.3.1 Sample preparation 215
4.1.3.2 Cyclic triaxial apparatus 215
4.1.3.3 Test procedure 217
4.1.4 Cyclic stress–strain response 219
4.1.5 Characterizations of M and D 221
r r
4.1.6 Meso-damage evolution analysis 223
4.1.7 Identifcation and extraction of cracks 225
4.1.8 Dilatancy behavior analysis 226
4.1.9 Conclusions 228
4.2 I nfuence of confning pressure on dynamic mechanical properties 230
4.2.1 Introduction 230
4.2.2 Materials and methods 231
4.2.2.1 Materials and sampling 231
4.2.2.2 X-ray CT machine 234
4.2.2.3 Loading apparatus 235
4.2.2.4 Testing scheme 237
4.2.3 Cyclic stress–strain responses 239
4.2.4 Damage and fracture observations 241
4.2.5 Analysis of meso-structural changes 243
4.2.6 Stress dilatancy behavior analysis 246
4.2.7 Conclusions 248
4.3 Infuence of rock blocks on fatigue damage evolution of bimrock 249
4.3.1 Introduction 249
4.3.2 Materials and experimental methods 251
4.3.2.1 Materials and sample preparation 251
4.3.2.2 X-ray CT machine 253
4.3.2.3 Loading apparatus 253
4.3.2.4 Test procedure 255
4.3.3 Testing program 257
4.3.4 Cyclic stress–strain response 258
4.3.5 General observations 260
4.3.6 Analysis of meso-structural changes 262
4.3.7 Stress dilatancy analysis 266
References 271
5 Flow and stress coupled characteristics of bimrock 275
5.1 T he effect of soil matrix on fow characteristics for  bimrocks 275
5.1.1 Introduction 275
5.1.2 Materials and specimen preparation 276
5.1.3 Test system and procedure 277
5.1.4 Seepage properties of matrix materials 279
5.1.5 Seepage properties of the SRM with clay matrix 280