单侧限压缩下预制裂隙试样力学特性及板裂化机制细观研究
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摘要
岩体板裂化破坏是地下工程中一种常见的破坏现象。采用等效岩体技术,将岩体中裂隙(平行于临空面)和岩块分别用光滑节理模型及颗粒体模型表征,通过试验和计算对比,研究单侧限压缩条件下裂隙岩体强度、裂纹分布、裂纹孕育演化规律及裂隙岩体板裂化形成机制。研究表明:(1)随裂隙数量的增加,岩体单侧限抗压强度近似呈线性降低的规律。(2)单侧限压缩下裂隙岩体中产生的裂纹可划分为Ⅰ型～Ⅴ型裂纹,其中Ⅰ型、Ⅱ型(剪切)裂纹是由加载端部效应导致,Ⅲ型～Ⅴ型裂纹由岩体板裂化破坏导致。(3)单侧限压缩下岩体板裂化破坏过程中,导致无侧限边界处岩体剥落的Ⅴ型裂纹最先产生,原生裂隙进一步扩展的Ⅳ型裂纹随后产生,最后产生的是板裂化现象向岩体深部发展的Ⅲ型裂纹。(4)各类裂隙试样在单侧限压缩下的声发射数量与破裂强度均近似服从高斯函数分布关系。
The slab failure of rock mass is one of the common destruction phenomena in underground engineering. Based upon equivalent rock mass(ERM) technique, the fracture(parallel to the free surface) and rock block are represented by the smooth-joint model and bonded-particle model, respectively. The strength, crack distribution, crack initiation and evolution, and slab failure formation mechanism of fractured rock mass under one side restriction(OSR) compression are studied by comparing experimental results and numerical modelling. With the increase in the number of fracture, the OSR compressive strength of rock mass exhibits linear decreasing. Under OSR loading, five types of cracks generated in rock mass can be identified. The type-Ⅰ and type-Ⅱ(shear) cracks are caused by the loading end effect, while the type-Ⅲ, type-Ⅳ and type-Ⅴ cracks are caused by slab failure of rock mass. In the process of slab failure, type-Ⅴ cracks which causes rock mass spalling at the unconfined boundary first occurs. Then type-Ⅳcracks result in the propagation of original fractures generate. Finally, the type-Ⅲ cracks generate, which indicates that the slab failure phenomenon is developing towards the interior of rock mass. In various specimens under OSR loading, the relationship between the acoustic emission(AE) quantities and crack magnitude approximates Gaussian function distribution.
The slab failure of rock mass is one of the common destruction phenomena in underground engineering. Based upon equivalent rock mass(ERM) technique, the fracture(parallel to the free surface) and rock block are represented by the smooth-joint model and bonded-particle model, respectively. The strength, crack distribution, crack initiation and evolution, and slab failure formation mechanism of fractured rock mass under one side restriction(OSR) compression are studied by comparing experimental results and numerical modelling. With the increase in the number of fracture, the OSR compressive strength of rock mass exhibits linear decreasing. Under OSR loading, five types of cracks generated in rock mass can be identified. The type-Ⅰ and type-Ⅱ(shear) cracks are caused by the loading end effect, while the type-Ⅲ, type-Ⅳ and type-Ⅴ cracks are caused by slab failure of rock mass. In the process of slab failure, type-Ⅴ cracks which causes rock mass spalling at the unconfined boundary first occurs. Then type-Ⅳcracks result in the propagation of original fractures generate. Finally, the type-Ⅲ cracks generate, which indicates that the slab failure phenomenon is developing towards the interior of rock mass. In various specimens under OSR loading, the relationship between the acoustic emission(AE) quantities and crack magnitude approximates Gaussian function distribution.
引文
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[19]周喻,吴顺川,高永涛,等.节理连通率对岩体力学特性影响的细观研究[J].岩土力学,2015,36(增刊2):29-36.ZHOU Yu,WU Shun-chuan,GAO Yong-tao,et al.Meso research on mechanical properties of rock mass affected by joint connectivity rate[J].Rock and Soil Mechanics,2015,36(Supp.2):29-36.
[20]周喻,吴顺川,许学良,等.岩石破裂过程中声发射特性的颗粒流分析[J].岩石力学与工程学报,2013,32(5):951-959.ZHOU Yu,WU Shun-chuan,XU Xue-liang,et al.Particle flow analysis of acoustic emission characteristics during rock failure process[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(5):951-959.
[21]王莉,谭卓英,周喻,等.煤样巴西劈裂试验中声发射特性的细观模拟[J].北京科技大学学报,2014,36(3):275-282.WANG Li,TAN Zhuo-ying,ZHOU Yu,et al.Mesoscopic simulative research on acoustic emission characteristic of coal sample in Brazilian test[J].Journal of University of Science and Technology Beijing,2014,36(3):275-282.
[2]徐林生,王兰生.二郎山公路隧道岩爆特征与防治措施研究[J].中国公路学报,2003,16(1):74-76.XU Lin-sheng,WANG Lan-sheng.Research on rockburst character and prevention measure of Erlang Mountain highway tunnel[J].China Journal of Highway and Transport,2003,16(1):74-76.
[3]ZHANG Chuan-qing,FENG Xia-ting,ZHOU Hui,et al.Case histories of four extremely intense rockbursts in deep tunnels[J].Rock Mechanics and Rock Engineering,2012,45(3):275-288.
[4]孙广忠,黄运飞.高边墙地下洞室洞壁围岩板裂化实例及其力学分析[J].岩石力学与工程学报,1988,7(1):15-24.SUN Guang-zhong,HUANG Yun-fei.An example slab-rending in the surrounding rock of underground excavation with high walls and its mechanical analysis[J].Chinese Journal of Rock Mechanics and Engineering,1988,7(1):15-24.
[5]潘岳,张勇,于广明.圆形硐室岩爆机制及其突变理论分析[J].应用数学和力学,2006,27(6):741-749.PAN Yue,ZHANG Yong,YU Guang-ming.Mechanism and catastrophe theory analysis of circular tunnel rockburst[J].Applied Mathematics and Mechanics,2006,27(6):741-749.
[6]STACEY T R.A simple extension strain criterion for fracture of brittle rock[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1981,18(6):469-474.
[7]杨圣奇,戴永浩,韩立军,等.断续预制裂隙脆性大理岩变形破坏特性单轴压缩试验研究[J].岩石力学与工程学报,2009,28(12):2391-2404.YANG Sheng-qi,DAI Yong-hao,HAN Li-jun,et al.Uniaxial compression experimental research on deformation and failure properties of brittle marble specimen with pre-existing fissures[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(12):2391-2404.
[8]LI Y P,CHEN L Z,WANG Y H.Experimental research on pre-cracked marble under compression[J].International Journal of Solid Sand Structures,2005,42(9/10):2505-2516.
[9]谭以安.岩爆岩石断口扫描电镜分析及岩爆渐进破坏过程[J].电子显微学报,1989,8(2):41-48.TAN Yi-an.Analysis of fractured face of rockburst with scanning electron microscope and its progressive failure process[J].Journal of Chinese Electron Microscopy Society,1989,8(2):41-48.
[10]张波,李术才,杨学英,等.含交叉裂隙岩体相似材料试件力学性能单轴压缩试验[J].岩土力学,2012,33(12):3674-3679.ZHANG Bo,LI Shu-cai,YANG Xue-ying,et al.Uniaxial compression tests on mechanical properties of rock mass similar material with cross-cracks[J].Rock and Soil Mechanics,2012,33(12):3674-3679.
[11]周辉,徐荣超,卢景景,等.板裂化模型试样失稳破坏及其裂隙扩展特征的试验研究[J].岩土力学,2015,36(增刊2):1-11.ZHOU Hui,XU Rong-chao,LU Jing-jing,et al.Experimental study of instability destruction and crack propagation characteristic of slab model specimen[J].Rock and Soil Mechanics,2015,36(Supp.2):1-11.
[12]朱道建,杨林德,蔡永昌.柱状节理岩体压缩破坏过程模拟及机制分析[J].岩石力学与工程学报,2009,28(4):716-724.ZHU Dao-jian,YANG Lin-de,CAI Yong-chang.Simulation of compressive failure process of columnar jointed rock mass and its failure mechanism analysis[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(4):716-724.
[13]TANG C A,YANG W T,FU Y F,et al.A new approach to numerical method of modelling geological processes and rock engineering problems-continuum to discontinuum and linearity to nonlinearity[J].Engineering Geology,1998,49(3-4):207-214.
[14]朱万成,张敏思,张洪训,等.节理岩体表征单元体尺寸确定的数值模拟[J].岩土工程学报,2013,35(6):1121-1127.ZHU Wan-cheng,ZHANG Min-si,ZHANG Hong-xun,et al.Numerical simulation for determining the size of representative element volume(REV)of jointed rock mass[J].Chinese Journal of Geotechnical Engineering,2013,35(6):1121-1127.
[15]李晓锋,李海波,夏祥,等.类节理岩石直剪试验力学特性的数值模拟研究[J].岩土力学,2016,37(2):583-591.LI Xiao-feng,LI Hai-bo,XIA Xiang,et al.Numerical simulation of mechanical characteristics of jointed rock in direct shear test[J].Rock and Soil Mechanics,2016,37(2):583-591.
[16]周辉,徐荣超,卢景景,等.深埋隧洞板裂屈曲岩爆机制及物理模拟试验研究[J].岩石力学与工程学报,2015,34(增刊2):3658-3666.ZHOU Hui,XU Rong-chao,LU Jing-jing,et al.Study on mechanisms and physical simulation experiment of slab buckling rockburst in deep tunnel[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(Supp.2):3658-3666.
[17]吴顺川,周喻,高利立,等.等效岩体技术在岩体工程中的应用[J].岩石力学与工程学报,2010,29(7):1435-1441.WU Shun-chuan,ZHOU Yu,GAO Li-li,et al.Application of equivalent rock mass technique to rock mass engineering[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(7):1435-1441.
[18]周喻,吴顺川,王莉,等.等效岩体技术在断续双节理岩石试件破裂机理细观分析中的应用[J].岩土力学,2013,34(10):2801-2809.ZHOU Yu,WU Shun-chuan,WANG Li,et al.Application of equivalent rock mass technique to mesoscopic analysis of fracture mechanism of rock specimen containing two intermittent joint[J].Rock and Soil Mechanics,2013,34(10):2801-2809.
[19]周喻,吴顺川,高永涛,等.节理连通率对岩体力学特性影响的细观研究[J].岩土力学,2015,36(增刊2):29-36.ZHOU Yu,WU Shun-chuan,GAO Yong-tao,et al.Meso research on mechanical properties of rock mass affected by joint connectivity rate[J].Rock and Soil Mechanics,2015,36(Supp.2):29-36.
[20]周喻,吴顺川,许学良,等.岩石破裂过程中声发射特性的颗粒流分析[J].岩石力学与工程学报,2013,32(5):951-959.ZHOU Yu,WU Shun-chuan,XU Xue-liang,et al.Particle flow analysis of acoustic emission characteristics during rock failure process[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(5):951-959.
[21]王莉,谭卓英,周喻,等.煤样巴西劈裂试验中声发射特性的细观模拟[J].北京科技大学学报,2014,36(3):275-282.WANG Li,TAN Zhuo-ying,ZHOU Yu,et al.Mesoscopic simulative research on acoustic emission characteristic of coal sample in Brazilian test[J].Journal of University of Science and Technology Beijing,2014,36(3):275-282.