Preface ........................................................ XI
About the author ............................................. XIII
PART I DEFORMATION AND FRACTURE OF ROCKS
Chapter 1. Precise measurements of fracture strength
of rocks under uniform compressive stress ............ 3
1.1. Present specimen design .................................... 4
1.2. Effect of length/diameter ratio to apparent strength
and fracture angle ......................................... 6
1.3. Comparison with the conventional method ................... 11
1.4. Decrease of the end effects by confining pressure ......... 12
References ..................................................... 15
Chapter 2. Deformation and failure of rocks under
confining pressure .................................. 17
2.1. Deformation characteristics ............................... 17
2.1.a. Experimental procedure ............................. 17
2.l.b. Stress-strain relation ............................. 19
2.1.с. Modulus of elasticity .............................. 23
2.1.d. Permanent strain ................................... 26
2.1.e. Effects of previous loading ........................ 26
2.1.e.1. Hydrostatic pressure ...................... 27
2.I.e.2. Axial compression ......................... 28
2.l.f. Yield stress ....................................... 29
2.1.g. Summary of the deformation characteristics ......... 31
2.2. Pressure dependence of compressive strength and
brittle-ductile transition ................................ 32
2.2.a. Relation between strength and confining
pressure ........................................... 32
2.2.b. The Coulomb-Mohr fracture criterion ................ 37
2.2.с. Brittle-ductile transition ......................... 43
References ................................................ 48
Chapter 3. Deformation and fracture of rocks under
the triaxial compression: The effect of
the intermediate principal stress ................... 51
3.1. History of compression experiments ........................ 51
3.1.a. Axial loading test under lateral pressure .......... 52
3.1.b. True triaxial compression test ..................... 52
3.2. Comparison between compression and extension under
confining pressure ........................................ 56
3.2.a. Introduction. 56 3.2.b. Experimental procedure ..... 57
3.2.b.l. Confined compression test ................. 57
3.2.b.2. Confined extension test ................... 58
3.2.с. Specimen materials ................................. 60
3.2.d. Experimental results ............................... 60
3.2.d.1. Examination ofisotropy and homogeneity
by uniaxial compression tests ............. 60
3.2.d.2. Comparison of confined compression
and extension tests ....................... 62
3.3. True triaxial compression experiments ..................... 66
3.3.a. Introduction ....................................... 66
3.3.b. Design of the true triaxial apparatus .............. 67
3.3.с. Specimen design and strain measurement ............. 72
3.3.d. Experimental procedure and rocks studied ........... 74
3.3.e. Experimental results (I) - Stress-strain curves
and fracture stresses .............................. 75
3.3.e.l. Dunham dolomite ........................... 76
3.3.e.2. Solnhofen limestone ....................... 82
З.З.е.З. Yamaguchi marble .......................... 88
3.3.e.4. Mizuho trachyte ........................... 94
3.3.e.5. Manazuru andesite ......................... 96
3.3.e.6. Inada granite ............................. 98
3.3.e.7. Orikabe monzonite ......................... 98
3.3.e.8. Summary ................................... 99
3.3.f. Experimental results (2) - Yield stresses ......... 103
3.3.f.1. Dunham dolomite .......................... 106
3.3.f.2. Solnhofen limestone ...................... 108
3.3.f.3. Yamaguchi marble ......................... 111
3.3.g. Failure criteria of rocks ......................... 113
3.3.g.1. Previous studies ......................... 113
3.3.g.2. Fracture criterion ....................... 122
3.3.g.3. Yield criterion .......................... 128
3.3.g.4. Summary .................................. 130
3.3.h. Ductility, fracture pattern and dilatancy ......... 131
3.3.h.1. Ductility and stress drop ................ 131
3.3.h.2. Fracture pattern ......................... 135
3.3.h.3. Dilatancy ................................ 151
3.3.i. Fracture of an inhomogeneous rock and an
anisotropic rock .................................. 161
3.3.1.1. Inhomogeneous rock ....................... 161
3.3.i.2. Anisotropic rock ......................... 165
3.3.J. Other recent experiments ......................... 181
3.3.к. Future problems ................................... 185
References ............................................... 186
Appendix ................................................. 190
PART II ACOUSTIC EMISSION (AE)
Chapter 4. AE Activity ........................................ 197
4.1. Introduction ............................................. 197
4.2. AE activity under some simple loadings ................... 198
4.3. Three patterns of AE activity ............................ 205
References .................................................... 215
Chapter 5. Source location of AE .............................. 217
5.1. Introduction ............................................. 217
5.2. Experimental procedure ................................... 218
5.2.a. Measurement of very high frequency elastic
waves ............................................. 218
5.2.b. Determination of source location of AE events ..... 220
5.2.b.l. One-dimensional case ..................... 220
5.2.b.2. Two-dimensional case ..................... 221
5.3. Experimental results ..................................... 222
5.3.a Granite (heterogeneous silicate rock) .............. 222
5.3.b. Andesite (moderately heterogeneous silicate
rock) ............................................. 231
5.3.с. Mizuho trachyte (nearly homogeneous silicate
rock) ............................................. 232
5.3.d. Yamaguchi marble with different grain sizes ....... 233
5.3.e. Fracture of a semi-infinite body by an inner
pressure source ................................... 234
References ............................................... 236
Chapter 6. Magnitude-frequency relation of AE events .......... 239
6.1. Introduction ............................................. 239
6.2. Experimental procedure and specimen materials ............ 239
6.3. The m value in the Ishimoto-Iida Equation ................ 244
6.4. Types of the magnitude-frequency relations and the
structure of the medium .................................. 248
6.5. Effects of measurements by different frequencies
and different dynamic ranges of acoustic waves ........... 250
References .................................................... 261
Chapter 7. AE Activity under cyclic loading ................... 263
7.1. Effect of tidal loading .................................. 263
7.1.a Introduction ....................................... 263
7.1.b. Observations of AE events directly above the
focal region of the 1980 earthquake swarm ......... 263
7.1.c. Seismic activity and ocean tide ................... 271
7.2. AE under cyclic compression .............................. 277
7.2.a. Experimental procedure ............................ 277
7.2.b. AE events under cyclic compression ................ 280
7.3. AE under cyclic bending .................................. 286
7.3.a. Introduction ...................................... 286
7.3.b. Experiment A ...................................... 286
7.3.с. Experiment В ...................................... 288
7.3.d. Concluding remarks ................................ 299
References .................................................... 302
Part III. ROCK FRICTION AND EARTHQUAKES
Chapter 8. Laboratory experiment of rock friction ............. 307
8.1. Introduction ............................................. 307
8.2. New design of a double-shear type apparatus .............. 308
8.3. Experimental result ...................................... 315
References .................................................... 320
Chapter 9. Typical stick-slip events in nature and
earthquakes ........................................ 321
9.1. Introduction ............................................. 321
9.2. Usu volcano and Unzen volcano, Japan ..................... 327
9.3. Sanriku-oki and Tokai-Nankai regions, Japan .............. 329
9.4. Stick-slip and fracture as an earthquake mechanism ....... 332
References .................................................... 333
Chapter 10.Some features in the occurrence of recent large
earthquakes ........................................ 335
10.1.Global pattern of seismic activity ....................... 335
10.2.Active and quiet periods in the main seismic zones ....... 339
10.2.a.Alaska -Aleutian - Kamchatka - N. Japan ........... 339
10.2.b.Alps ~ Himalaya - Sunda ........................... 341
10.3.Some precursory seismic activity of recent large
shallow earthquakes ...................................... 343
10.3.a.Introduction ...................................... 343
10.З.Ь.2001 Bhuj (India) earthquake ...................... 344
10.3.с.2003 Tokachi-oki (Japan) earthquake ............... 346
References .................................................... 357
Subject index ................................................. 359
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