硬岩应力–应变门槛值特点及产生机制
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摘要
详细总结岩石应力门槛值(起裂强度ci?、损伤强度cd?和峰值强度f?)的物理意义和计算方法,以花岗岩和大理岩为研究对象进行不同围压的常规三轴试验,计算分析ci?,cd?和f?值,以及各个门槛值对应的轴向应变、侧向应变和体积应变的变化规律,重点讨论轴向应变和侧向应变的特点和产生机制,分析结果发现:花岗岩的cc?/f?,ci?/f?,cd?/f?分别位于0.10~0.19,0.40~0.59,0.77~0.82区间内,大理岩相应的应力比位于0.10~0.25,0.47~0.64,0.82~0.92内,不同岩石或相同岩石门槛值应力比的差异可能由于矿物成分、赋存环境、开挖损伤造成;2种岩石应力门槛值及各自对应的轴向应变随围压近似呈线性递增,并且应力和轴向应变随围压的变化曲线非常相似;侧向应变在达到cd?之前增长缓慢,在达到cd?之后急剧增加,而轴向应变在整个加载过程稳步增加;围压、cd?和对应的损伤体积应变存在内在关联性,相互关系可用线性或二项式拟合。
The physical significance and the calculation methods of stress thresholds(the crack initiation stressci?,the crack damage stresscd? and the peak stressf?) for rock were summarized in detail. The conventional triaxial compression tests at various confining pressures were conducted on the typical hard rock of granite and marble. The threshold values ci?,cd? andf? together with the axial,lateral and volumetric strains corresponding to the stress thresholds under various confining pressures were calculated and analyzed. The characteristics and the mechanism of occurrence of the axial and lateral strains were the focus of the discussion. The ratios of cc? /f?,ci? /f?,cd? /f? was found in the range of 0.10–0.19,0.40–0.59,0.77–0.82 for granite respectively,and in the range of 0.10–0.25,0.47–0.64,0.82–0.92 for marble under different confining pressures. The difference of stress ratios for different rocks or for the same kind of rock but sampled at different locations may be due to the mineral compositions,geological environments and excavation damage. The stress thresholds and the corresponding axial strain of the two rocks increased approximately linearly with the confining pressure. The lateral strain increased slowly when stress was belowcd? but increased sharply aftercd? was exceeded. The axial strain showed a trend of steady increasing in the entire loading process. The relationship of the confining pressure,cd? and the volumetric strain corresponding tocd? were interrelated inherently,which was fitted with a linear relation or a quadratic polynomial.
The physical significance and the calculation methods of stress thresholds(the crack initiation stressci?,the crack damage stresscd? and the peak stressf?) for rock were summarized in detail. The conventional triaxial compression tests at various confining pressures were conducted on the typical hard rock of granite and marble. The threshold values ci?,cd? andf? together with the axial,lateral and volumetric strains corresponding to the stress thresholds under various confining pressures were calculated and analyzed. The characteristics and the mechanism of occurrence of the axial and lateral strains were the focus of the discussion. The ratios of cc? /f?,ci? /f?,cd? /f? was found in the range of 0.10–0.19,0.40–0.59,0.77–0.82 for granite respectively,and in the range of 0.10–0.25,0.47–0.64,0.82–0.92 for marble under different confining pressures. The difference of stress ratios for different rocks or for the same kind of rock but sampled at different locations may be due to the mineral compositions,geological environments and excavation damage. The stress thresholds and the corresponding axial strain of the two rocks increased approximately linearly with the confining pressure. The lateral strain increased slowly when stress was belowcd? but increased sharply aftercd? was exceeded. The axial strain showed a trend of steady increasing in the entire loading process. The relationship of the confining pressure,cd? and the volumetric strain corresponding tocd? were interrelated inherently,which was fitted with a linear relation or a quadratic polynomial.
引文
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[2]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.
[3]MARTIN C D.The strength of massive Lac du Bonnet granite aroundunderground opening[Ph.D.Thesis][D].Winnipeg:University of Manitoba,1993.
[4]MARTIN C D,READ R S,MARTINO J B.Observations of brittle failure around a circular test tunnel[J].International Journal of Rock Mechanics and Mining Sciences,1997,34(7):1 065–1 073.
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[6]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.
[7]张晓平,王思敬,韩庚友,等.岩石单轴压缩条件下裂纹扩展试验研究——以片状岩石为例[J].岩石力学与工程学报,2011,30(9):1 772–1 781.(ZHANG Xiaoping,WANG Sijing,HAN Gengyou,et al.Crack propagation study of rock based on uniaxial compressive test—A case study of schistose rock[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(9):1 772–1 781.(in Chinese))
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[11]黄达,黄润秋,张永兴.粗晶大理岩单轴压缩力学特性的静态加载速率效应及能量机制试验研究[J].岩石力学与工程学报,2012,31(2):245–255.(HUANG Da,HUANG Runqiu,ZHANG Yongxing.Experimental investigations on static loading rate effects on mechanical properties and energy mechanism of coarse crystal grain marble under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(2):245–255.(in Chinese))
[12]汪斌,朱杰兵,严鹏,等.大理岩损伤强度的识别及基于损伤控制的参数演化规律[J].岩石力学与工程学报,2012,31(增2):3 967–3 973.(WANG Bin,ZHU Jiebing,YAN Peng,et al.Damage strength determination of marble and its parameters evalution based on damage control test[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(Supp.2):3 967–3 973.(in Chinese))
[13]梁昌玉,李晓,王声星,等.岩石单轴压缩应力–应变特征的率相关性及能量机制试验研究[J].岩石力学与工程学报,2012,31(9):1 830–1 838.(LIANG Changyu,LI Xiao,WANG Shengxing,et al.Experimental investigations on rate-dependent stress-strain characteristics and energy mechanism of rock under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(9):1 830–1 838.(in Chinese))
[14]梁昌玉,李晓,张辉,等.中低应变率范围内花岗岩单轴压缩特性的尺寸效应研究[J].岩石力学与工程学报,2013,32(3):528–536.(LIANG Changyu,LI Xiao,ZHANG Hui,et al.Research on size effect of uniaxial compression properties of granite under medium and low strain rates[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(3):528–536.(in Chinese))
[15]周辉,杨凡杰,张传庆,等.考虑围压效应的大理岩弹塑性耦合力学模型研究[J].岩石力学与工程学报,2012,31(12):2 389–2 399.(ZHOU Hui,YANG Fanjie,ZHANG Chuanqing,et al.An elastoplastic coupling mechanical model for marble considering confining pressure effect[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(12):2 389–2 399.(in Chinese))
[16]IRWIN G R.Fracture mechanics.structural mechanics[M].[S.l.]:Pergamon Press,1960:557–592.
[17]BIENIAWSKI Z T.Mechanism of brittle fracture of rock,Parts I,II and III[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1967,4(4):395–430.
[18]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.
[19]黄书岭.高应力下脆性岩石的力学模型与工程应用研究[博士学位论文][D].武汉:中国科学院武汉岩土力学研究所,2008.(HUANG Shuling.Study on mechanical model of brittle rock under high stress condition and its engineering applications[Ph.D.Thesis][D].Wuhan:Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,2008.(in Chinese))
[2]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.
[3]MARTIN C D.The strength of massive Lac du Bonnet granite aroundunderground opening[Ph.D.Thesis][D].Winnipeg:University of Manitoba,1993.
[4]MARTIN C D,READ R S,MARTINO J B.Observations of brittle failure around a circular test tunnel[J].International Journal of Rock Mechanics and Mining Sciences,1997,34(7):1 065–1 073.
[5]CAI M,KAISER P K,TASAKA Y M,et al.Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(5):833–847.
[6]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.
[7]张晓平,王思敬,韩庚友,等.岩石单轴压缩条件下裂纹扩展试验研究——以片状岩石为例[J].岩石力学与工程学报,2011,30(9):1 772–1 781.(ZHANG Xiaoping,WANG Sijing,HAN Gengyou,et al.Crack propagation study of rock based on uniaxial compressive test—A case study of schistose rock[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(9):1 772–1 781.(in Chinese))
[8]刘宁,张春生,褚卫江.锦屏深埋大理岩破裂特征与损伤演化规律[J].岩石力学与工程学报,2012,31(8):1 606–1 613.(LIU Ning,ZHANG Chunsheng,CHU Weijiang.Fracture characteristics and damage evolution law of Jinping deep marble[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(8):1 606–1 613.(in Chinese))
[9]张春生,陈祥荣,侯靖,等.锦屏二级水电站深埋大理岩力学特性研究[J].岩石力学与工程学报,2010,29(10):1 999–2 009.(ZHANG Chunsheng,CHEN Xiangrong,HOU Jing,et al.Study of mechanical behavior of deep-buried marble at Jinping II hydropower station[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(10):1 999–2 009.(in Chinese))
[10]朱泽奇,盛谦,冷先伦,等.三峡花岗岩起裂机制研究[J].岩石力学与工程学报,2007,26(12):2 570–2 575.(ZHU Zeqi,SHENG Qian,LENG Xianlun,et al.Study of crack initiation mechanism of Three Gorges granite[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(12):2 570–2 575.(in Chinese))
[11]黄达,黄润秋,张永兴.粗晶大理岩单轴压缩力学特性的静态加载速率效应及能量机制试验研究[J].岩石力学与工程学报,2012,31(2):245–255.(HUANG Da,HUANG Runqiu,ZHANG Yongxing.Experimental investigations on static loading rate effects on mechanical properties and energy mechanism of coarse crystal grain marble under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(2):245–255.(in Chinese))
[12]汪斌,朱杰兵,严鹏,等.大理岩损伤强度的识别及基于损伤控制的参数演化规律[J].岩石力学与工程学报,2012,31(增2):3 967–3 973.(WANG Bin,ZHU Jiebing,YAN Peng,et al.Damage strength determination of marble and its parameters evalution based on damage control test[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(Supp.2):3 967–3 973.(in Chinese))
[13]梁昌玉,李晓,王声星,等.岩石单轴压缩应力–应变特征的率相关性及能量机制试验研究[J].岩石力学与工程学报,2012,31(9):1 830–1 838.(LIANG Changyu,LI Xiao,WANG Shengxing,et al.Experimental investigations on rate-dependent stress-strain characteristics and energy mechanism of rock under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(9):1 830–1 838.(in Chinese))
[14]梁昌玉,李晓,张辉,等.中低应变率范围内花岗岩单轴压缩特性的尺寸效应研究[J].岩石力学与工程学报,2013,32(3):528–536.(LIANG Changyu,LI Xiao,ZHANG Hui,et al.Research on size effect of uniaxial compression properties of granite under medium and low strain rates[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(3):528–536.(in Chinese))
[15]周辉,杨凡杰,张传庆,等.考虑围压效应的大理岩弹塑性耦合力学模型研究[J].岩石力学与工程学报,2012,31(12):2 389–2 399.(ZHOU Hui,YANG Fanjie,ZHANG Chuanqing,et al.An elastoplastic coupling mechanical model for marble considering confining pressure effect[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(12):2 389–2 399.(in Chinese))
[16]IRWIN G R.Fracture mechanics.structural mechanics[M].[S.l.]:Pergamon Press,1960:557–592.
[17]BIENIAWSKI Z T.Mechanism of brittle fracture of rock,Parts I,II and III[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1967,4(4):395–430.
[18]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.
[19]黄书岭.高应力下脆性岩石的力学模型与工程应用研究[博士学位论文][D].武汉:中国科学院武汉岩土力学研究所,2008.(HUANG Shuling.Study on mechanical model of brittle rock under high stress condition and its engineering applications[Ph.D.Thesis][D].Wuhan:Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,2008.(in Chinese))