Acoustic characterization of crack damage evolution in sandstone deformed under conventional and true triaxial loading

被引:112
作者
Browning, J. [1 ]
Meredith, P. G. [1 ]
Stuart, C. E. [1 ]
Healy, D. [2 ]
Harland, S. [2 ]
Mitchell, T. M. [1 ]
机构
[1] UCL, Dept Earth Sci, London, England
[2] Univ Aberdeen, Sch Geosci, Aberdeen, Scotland
关键词
crack; acoustic; triaxial; damage; velocity; elastic; VELOCITY ANISOTROPY; SPATIAL EVOLUTION; ELASTIC-MODULI; ROCK STRENGTH; FAILURE; TIME; LOCALIZATION; DEFORMATION; MECHANICS; EMISSION;
D O I
10.1002/2016JB013646
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
We present a comparative study of crack damage evolution in dry sandstone under both conventional (sigma(1)>sigma(2)=sigma(3)), and true triaxial (sigma(1)>sigma(2)>sigma(3)) stress conditions using results from measurements made on cubic samples deformed in three orthogonal directions with independently controlled stress paths. To characterize crack damage, we measured the changes in ultrasonic compressional and shear wave velocities in the three principal directions, together with the bulk acoustic emission (AE) output contemporaneously with stress and strain. We use acoustic wave velocities to model comparative crack densities and orientations. In essence, we create two end-member crack distributions; one displaying cylindrical transverse isotropy (conventional triaxial) and the other planar transverse isotropy (true triaxial). Under the stress conditions in our experiments we observed an approximately fivefold decrease in the number of AE events between the conventional and true triaxial cases. When taken together, the AE data, the velocities, and the crack density data indicate that the intermediate principal stress suppresses the total number of cracks and restricts their growth to orientations subnormal to the minimum principal stress. However, the size of individual cracks remains essentially constant, controlled by the material grain size. Crack damage is only generated when the differential stress exceeds some threshold value. Cyclic loading experiments show that further damage commences only when that previous maximum differential stress is exceeded, regardless of the mean stress, whether this is achieved by increasing the maximum principal stress or by decreasing the minimum principal stress.
引用
收藏
页码:4395 / 4412
页数:18
相关论文
共 52 条
[1]   EFFECT OF ORIENTED CRACKS ON SEISMIC VELOCITIES [J].
ANDERSON, DL ;
MINSTER, B ;
COLE, D .
JOURNAL OF GEOPHYSICAL RESEARCH, 1974, 79 (26) :4011-4015
[2]  
[Anonymous], 2005, EXPT ROCK DEFORMATIO, DOI [DOI 10.1007/B137431, DOI 10.1007/3-540-26339-X_7]
[3]  
[Anonymous], 1997, INT J ROCK MECH MIN
[4]   MICROCRACKING DURING TRIAXIAL DEFORMATION OF POROUS ROCKS MONITORED BY CHANGES IN ROCK PHYSICAL-PROPERTIES .1. ELASTIC-WAVE PROPAGATION MEASUREMENTS ON DRY ROCKS [J].
AYLING, MR ;
MEREDITH, PG ;
MURRELL, SAF .
TECTONOPHYSICS, 1995, 245 (3-4) :205-221
[5]   Compaction localization in porous sandstones: spatial evolution of damage and acoustic emission activity [J].
Baud, P ;
Klein, E ;
Wong, TF .
JOURNAL OF STRUCTURAL GEOLOGY, 2004, 26 (04) :603-624
[6]   Permeability evolution during triaxial compaction of an anisotropic porous sandstone [J].
Baud, Patrick ;
Meredith, Philip ;
Townend, Edward .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2012, 117
[7]   Time-dependent recovery of microcrack damage and seismic wave speeds in deformed limestone [J].
Brantut, Nicolas .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2015, 120 (12) :8088-8109
[8]   MICROCRACK FORMATION AND MATERIAL SOFTENING IN ROCK MEASURED BY MONITORING ACOUSTIC EMISSIONS [J].
COX, SJD ;
MEREDITH, PG .
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES & GEOMECHANICS ABSTRACTS, 1993, 30 (01) :11-24
[9]   STRENGTH CHARACTERISTICS AND SHEAR ACOUSTIC ANISOTROPY OF ROCK CORE SUBJECTED TO TRUE TRIAXIAL COMPRESSION [J].
CRAWFORD, BR ;
SMART, BGD ;
MAIN, IG ;
LIAKOPOULOUMORRIS, F .
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES & GEOMECHANICS ABSTRACTS, 1995, 32 (03) :189-200
[10]   The application of critical state soil mechanics to the mechanical behaviour of porous sandstones [J].
Cuss, RJ ;
Rutter, EH ;
Holloway, RF .
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, 2003, 40 (06) :847-862