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| DAMAGE AND DILATION CHARACTERISTICS OF DEEP GRANITE AT BEISHAN UNDER CYCLIC LOADING-UNLOADING CONDITIONS
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| ZHAO Xingguang1，LI Pengfei2，MA Like1，SU Rui1，WANG Ju1 |
| (1. Beijing Research Institute of Uranium Geology，Beijing 100029，China；2. School of Civil and Environmental Engineering，University of Science and Technology Beijing，Beijing 100083，China) |
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Abstract Damage and dilation characteristics of the granite from great depth at Beishan under triaxial cyclic loading-unloading conditions were investigated using the rock mechanical test machine MTS815 and the acoustic emission(AE) measurement system PCI–2. Complete stress-strain curves associated with the accumulative AE hits and the 3D distributions of AE events were analyzed. The mechanisms of fracture evolution of the rock samples during deformation were revealed. The variation of dilation angle with plastic shear strain was characterized and the confining stress dependent dilation behavior was discussed according to the established plastic strain locus. The 3D distributions of AE events in the process of loading-unloading indicated that the maximum gradient of crack growth occurred at the stage of strain softening. In this stage，the cyclic loading was the main factor triggering the drastic damage and the macro coalescence of fractures in the rock. At the stage of residual deformation，there were almost no newly generated cracks. The incremental AE events at this stage were primarily attributed to the frictional sliding of the shear plane. This explained why the volumetric strain rate approached zero near the end of loading. Compared with the loading process，the repeated unloading had smaller effects on the development of cracks. Due to the different states of crack propagation，a significant difference in AE characteristics before and after the crack damage stress( ) were observed. The calculated post-peak dilation angle deceased with the increasing of the plastic shear strain and its decaying gradient decreased with the increase of the confining stresses. A model for dilation angle was established using an exponential function to reasonably describe the dilation behaviors of Beishan granite.
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Received: 05 May 2014
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| [1] WANG J. High-level radioactive waste disposal in China：update 2010[J]. Journal of Rock Mechanics and Geotechnical Engineering，2010，2(1)：1–11.
[2] 潘自强，钱七虎. 高放废物地质处置战略研究[M]. 北京：原子能出版社岩，2009：1–10.(PAN Ziqiang，QIAN Qihu. Strategic research for deep geological disposal of high level radioactive waste[M]. Beijing：Atomic Energy Press，2009：1–10.(in Chinese))
[3] 王 驹，陈伟明，苏 锐，等. 高放废物地质处置及其若干关键科学问题[J]. 岩石力学与工程学报，2006，25(4)：801–812.(WANG Ju，CHEN Weiming，SU Rui，et al. Geological disposal of high-level radioactive waste in and its key scientific issues[J]. Chinese Journal of Rock Mechanics and Engineering，2006，25(4)：801–812.(in Chinese))
[4] BRACE W F，PAULDING B W，SCHOLZ C H. Dilatancy in the fracture of crystalline rocks[J]. Journal of Geophysical Research，1966，71(16)：3 939–3 953.
[5] BIENIAWSKI Z T. Mechanism of brittle fracture of rock，parts I，II and III[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanical Abstracts，1967，4(4)：395–430.
[6] MARTIN C D，CHANDLER N A. The progressive fracture of Lac du Bonnet granite[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanical Abstracts，1994，31(6)：643–659.
[7] EBERHARDT E，STEAD D，STIMPSON B，et al. Identifying crack initiation and propagation thresholds in brittle rock[J]. Canadian Geotechnical Journal，1998，35(2)：222–233.
[8] ALEJANO L R，ALONSO E. Considerations of the dilatancy angle in rocks and rock masses[J]. International Journal of Rock Mechanics and Mining Sciences，2005，42(4)：481–507.
[9] ZHAO X G，CAI M. A dilation angle model for rocks[J]. International Journal of Rock Mechanics and Mining Sciences，2010，47(3)：368–384.
[10] ZHAO X G，CAI M. Influence of plastic shear strain and confinement- dependent rock dilation on rock failure and displacement near an excavation boundary[J]. International Journal of Rock Mechanics and Mining Sciences，2010，47 (5)：723–738.
[11] 赵星光，蔡美峰，蔡 明，等. 地下工程岩体剪胀与锚杆支护的相互影响[J]. 岩石力学与工程学报，2010，29(10)：2 056–2 062. (ZHAO Xingguang，CAI Meifeng，CAI Ming，et al. Mutual influence between rock mass dilation and rebar support around underground excavations[J]. Chinese Journal of Rock Mechanics and Engineering， 2010，29(10)：2 056–2 062.(in Chinese))
[12] 赵星光，蔡 明，蔡美峰. 剪胀对地下工程岩体位移的影响——以加拿大Donkin-Morien隧道为例[J]. 岩石力学与工程学报，2010，29(11)：2 185–2 195.(ZHAO Xingguang，CAI Ming，CAI Meifeng. Influence of dilation on rock mass displacement around underground excavations—a case study of the Donkin-Morien tunnel in Canada[J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(11)：2 185–2 195.(in Chinese))
[13] ZHAO X G，CAI M F，CAI M. Considerations of rock dilation on modeling failure and deformation of hard rocks—a case study of the mine-by test tunnel in Canada[J]. Journal of Rock Mechanics and Geotechnical Engineering，2010，2(4)：338–349.
[14] ELLIOTT G M，BROWN E T. Further development of a plasticity approach to yield in porous rock[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanical Abstracts，1986，23(2)：151–156.
[15] MEDHURST T P. Estimation of in-situ strength and deformability of coal for engineering design[Ph. D. Thesis][D]. Australia：University of Queensland，1996.
[16] MARTIN C D，CHANDLER N A. The progressive fracture of Lac du Bonnet granite[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1994，31(6)：643–659.
[17] EBERHARDT E，STEAD D，STIMPSON B. Quantifying progressive pre-peak brittle fracture damage in rock during uniaxial compression[J]. International Journal of Rock Mechanics and Mining Sciences，1999，36(3)：361–380.
[18] XIAO J Q，DING D X，JIANG F L，et al. Fatigue damage variable and evolution of rock subjected to cyclic loading[J]. International Journal of Rock Mechanics and Mining Sciences，2010，47(3)：461–468.
[19] QIU S L，FENG X T，XIAO J Q，et al. An experimental study on the pre-peak unloading damage evolution of marble[J]. Rock Mechanics and Rock Engineering，2014，47(2)：401–419.
[20] ZHAO X G，CAI M，WANG J，et al. Damage stress and acoustic emission characteristics of the Beishan granite[J]. International Journal of Rock Mechanics and Mining Sciences，2013，64：258–269.
[21] 刘泉声，刘恺德，朱杰兵，等. 高应力下原煤三轴压缩力学特性研究[J]. 岩石力学与工程学报，2014，33(1)：24–34.(LIU Quansheng，LIU Kaide，ZHU Jiebing，et al. Study of mechanical properties of raw coal under high stress with triaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering，2014，33(1)：24–34.(in Chinese))
[22] VERMEER PA，DE BORST R. Non-associated plasticity for soils，concrete and rock[J]. Heron，1984，29(3)：1–64.
[23] 赵星光，蔡 明，蔡美峰. 岩石剪胀角模型与验证[J]. 岩石力学与工程学报，2010，29(5)：970–981.(ZHAO Xingguang，CAI Ming，CAI Meifeng. A rock dilation angle model and its verification[J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(5)：970–981.(in Chinese))
[24] CROUCH S L. Experimental determination of volumetric strains in failed rock[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1970，7(6)：589–603. |
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2014, Vol. 33 
