单裂隙花岗岩破坏强度及裂纹扩展特征研究
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摘要
为了研究裂隙花岗岩强度特征及破坏过程,对裂隙花岗岩进行单轴压缩下的声发射测试,基于应力–应变数据、声发射多参量特征、摄像记录综合分析裂纹扩展特征及其相互变化关系。研究结果表明:裂隙倾角?对起裂应力和破坏强度影响较大,弹性模量和起裂应力随?单调增大;裂隙花岗岩应力–应变曲线在峰前呈阶梯状上升,尤其当?较小时,发生多次应力突降,应力降对应模量的快速弱化、AE事件率和能量率的剧烈凸起;AE事件率表现出明显的三阶段特征,随着?的增大,三阶段特征逐渐弱化,岩石的脆性破坏程度增大,应力降和AE凸起数量逐渐减小,AE事件率和能量率最大值对应的应力逐渐增大;相比AE事件,能量率最大值的发生更靠近峰值强度,且变化更剧烈;AE震源时空演化很好地描绘了裂纹的三维扩展区域和分布规律,稳定增长期震源数量和幅值均较小,高速增长期大幅值震源数量快速增加,尤其是在临近破坏前。
In order to study the strength characteristics and failure process of fractured rocks,uniaxial compression tests together with AE monitoring were conducted on granites containing a single fissure. The stress-strain data,multi-parameters of AE and video recording were used to analyze the characteristics of crack evolution and their correlations. The results show that the fissure angle ? has a bigger influence on crack initiation stress and failure strength. The modulus and crack initiation stress increase monotonously with ?. The stress-strain curves of fractured rocks rise stepwise before the peak strength,and stress drop occurs several times when ? is small. It?s revealed that the stress drop coincides with the deterioration of modulus,sharp bulge of AE event rate and energy rate. AE event evolution of fractured granites is divided into three stages,with the increase of ?,the three-stages characteristic gradually weakens and the brittle failure increases. Moreover,the number of stress drop and AE bulges gradually decrease,but stress levels corresponding to the maximum of AE rate keep increasing. Compared with AE event,the maximum energy rate occurs closer to the peak stress,and AE energy changes more severely.The spatiotemporal evolution of AE hypocenters depicts the three-dimensional propagation region and distribution of cracks. The amplitude of hypocenters occurred at the stable growth period are small,and the number of large-amplitude hypocenters increases rapidly after the high-speed growth period,especially prior to the failure.
In order to study the strength characteristics and failure process of fractured rocks,uniaxial compression tests together with AE monitoring were conducted on granites containing a single fissure. The stress-strain data,multi-parameters of AE and video recording were used to analyze the characteristics of crack evolution and their correlations. The results show that the fissure angle ? has a bigger influence on crack initiation stress and failure strength. The modulus and crack initiation stress increase monotonously with ?. The stress-strain curves of fractured rocks rise stepwise before the peak strength,and stress drop occurs several times when ? is small. It?s revealed that the stress drop coincides with the deterioration of modulus,sharp bulge of AE event rate and energy rate. AE event evolution of fractured granites is divided into three stages,with the increase of ?,the three-stages characteristic gradually weakens and the brittle failure increases. Moreover,the number of stress drop and AE bulges gradually decrease,but stress levels corresponding to the maximum of AE rate keep increasing. Compared with AE event,the maximum energy rate occurs closer to the peak stress,and AE energy changes more severely.The spatiotemporal evolution of AE hypocenters depicts the three-dimensional propagation region and distribution of cracks. The amplitude of hypocenters occurred at the stable growth period are small,and the number of large-amplitude hypocenters increases rapidly after the high-speed growth period,especially prior to the failure.
引文
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[19]LEI X,MASUDA K,NISHIZAWA O,et al.Detailed analysis of acoustic emission activity during catastrophic fracture of faults in rock[J].Journal of Structural Geology,2004,26(2):247-258.
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[21]裴建良,刘建锋,左建平,等.基于声发射定位的自然裂隙动态演化过程研究[J].岩石力学与工程学报,2013,32(4):696-704.(PEIJianliang,LIU Jianfeng,ZUO Jianping,et al.Investigation on dynamic evolution process of natural fractures based on acoustic emission position[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(4):696-704.(in Chinese))
[22]LOCKNER D.The role of acoustic emission in the study of rock fracture[J].International Journal of Rock Mechanics and Mining Science and Geomechanics Abstracts,1993,30(7):883-899.
[23]蒋海昆,马胜利,张流,等.雁列式断层组合变形过程中的声发射活动特征[J].地震学报,2002,24(4):385-396.(JIANG Haikun,MA Shengli,ZHANG Liu,et al.Spatiotemporal characteristics of acoustic emission during the deformation of rock samples with compressional and extensional en-echelon fault pattern[J].Acta Seismologica Sinica,2002,24(4):385-396.(in Chinese))
[24]任利,谢和平,谢凌志,等.基于断裂力学的裂隙岩体强度分析初探[J].工程力学,2013,30(2):156-162.(REN Li,XIE Heping,XIE Lingzhi,et al.Preliminary study on strength of cracked rock specimen based on fracture mechanics[J].Engineering Mechanics,2013,30(2):156-162.(in Chinese))
[25]张国凯,李海波,夏祥,等.单轴加载条件下花岗岩声发射及波传播特性研究[J].岩石力学与工程学报,2017,36(5):1 133-1 144.(ZHANG Guokai,LI Haibo,XIA Xiang,et al.Experiment study on acoustic emission and wave propagation in granite under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(5):1 133-1 144.(in Chinese))
[26]GEIGER L.Probability method for the determination of earthquake epicenters from the arrival time only[J].Bulletin of St.Louis University,1912,8(1):56-71.
[2]蒋明镜,陈贺,张宁,等.含双裂隙岩石裂纹演化机理的离散元数值分析[J].岩土力学,2014,35(11):3 259-3 268.(JIANGMingjing,CHEN He,ZHANG Ning,et al.Distinct element numerical analysis of crack evolution in rocks containing pre-existing double flaw[J].Rock and Soil Mechanics,2014,35(11):3 259-3 268.(in Chinese))
[3]陈新,廖志红,李德建.节理倾角及连通率对岩体强度、变形影响的单轴压缩试验研究[J].岩石力学与工程学报,2011,30(4):781-789.(CHEN Xin,LIAO Zhihong,LI Dejian.Experimental study of effects of joint inclination angle and connectivity rate on strength and deformation properties of rock masses under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(4):781-789.(in Chinese))
[4]LAJTAI E Z.Brittle fracture in compression[J].International Journal of Fracture,1974,10(4):525-536.
[5]肖桃李,李新平,贾善坡.含2条断续贯通预制裂隙岩样破坏特性的三轴压缩试验研究[J].岩石力学与工程学报,2015,34(12):2 455-2 461.(XIAO Taoli,LI Xinpin,JIA Shanpo.Failure characteristics of rock with two pre-existing transfixion cracks under triaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(12):2 455-2 461.(in Chinese))
[6]WONG L N Y,EINSTEIN H H.Crack coalescence in molded gypsum and carrara marble:part 1.macroscopic observations and interpretation[J].Rock Mechanics and Rock Engineering,2009,42(3):475-511.
[7]WONG L N Y,EINSTEIN H H.Crack coalescence in molded gypsum and Carrera marble:part 2-microscopic observations and interpretation[J].Rock Mechanics and Rock Engineering,2009,42(3):512-545.
[8]刘红岩,黄妤诗,李楷兵,等.预制节理岩体试件强度及破坏模式的试验研究[J].岩土力学,2013,34(5):1 235-1 241.(LIU Hongyan,HUANG Yushi,LI Kaibing,et al.Experimental study on strength and failure mode of prefabricated jointed rock mass specimens[J].Rock and Soil Mechanics,2013,34(5):1 235-1 241.(in Chinese))
[9]SHEN B,STEPHANSSON O,EINSTEIN H H,et al.Coalescence of fractures under shear stresses in experiments[J].Journal of Geophysical Research Solid Earth,1995,100(B4):5 975-5 990.
[10]BOBET A,EINSTEIN H H.Fracture coalescence in rock-type materials under uniaxial and biaxial compression[J].International Journal of Rock Mechanics and Mining Sciences,1998,35(7):863-888.
[11]LI Y P,CHEN L Z,WANG Y H.Experimental research on pre-cracked marble under compression[J].International Journal of Solids and Structures,2005,42(9):2 505-2 516.
[12]HUANG J,CHEN G,ZHAO Y,et al.An experimental study of the strain field development prior to failure of a marble plate under compression[J].Tectonophysics,1990,175(1/3):269-284.
[13]YANG S Q,JING H W.Strength failure and crack coalescence behavior of brittle sandstone samples containing a single fissure under uniaxial compression[J].International Journal of Fracture,2011,168(2):227-250.
[14]YANG S Q,TIAN W L,HUANG Y H,et al.An Experimental and numerical study on cracking behavior of brittle sandstone containing two non-coplanar fissures under uniaxial compression[J].Rock Mechanics and Rock Engineering,2016,49(4):1 497-1 515.
[15]LEE H,JEON S.An experimental and numerical study of fracture coalescence in pre-cracked specimens under uniaxial compression[J].International Journal of Solids and Structures,2011,48(6):979-999.
[16]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.
[17]DIEDERICHS M S,KAISER P K,EBERHARDT E.Damage initiation and propagation in hard rock during tunnelling and the influence of near-face stress rotation[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(5):785-812.
[18]GANNE P,VERVOORT A,WEVERS M.Quantification of pre-peak brittle damage:correlation between acoustic emission and observed micro-fracturing[J].International Journal of Rock Mechanics and Mining Sciences,2007,44(5):720-729.
[19]LEI X,MASUDA K,NISHIZAWA O,et al.Detailed analysis of acoustic emission activity during catastrophic fracture of faults in rock[J].Journal of Structural Geology,2004,26(2):247-258.
[20]赵兴东,李元辉,袁瑞甫,等.基于声发射定位的岩石裂纹动态演化过程研究[J].岩石力学与工程学报,2007,26(5):944-950.(ZHAO Xingdong,LI Yuanhui,YUAN Ruifu,et al.Study on crack dynamic propagation process of rock samples based on acoustic emission location[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(5):944-950.(in Chinese))
[21]裴建良,刘建锋,左建平,等.基于声发射定位的自然裂隙动态演化过程研究[J].岩石力学与工程学报,2013,32(4):696-704.(PEIJianliang,LIU Jianfeng,ZUO Jianping,et al.Investigation on dynamic evolution process of natural fractures based on acoustic emission position[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(4):696-704.(in Chinese))
[22]LOCKNER D.The role of acoustic emission in the study of rock fracture[J].International Journal of Rock Mechanics and Mining Science and Geomechanics Abstracts,1993,30(7):883-899.
[23]蒋海昆,马胜利,张流,等.雁列式断层组合变形过程中的声发射活动特征[J].地震学报,2002,24(4):385-396.(JIANG Haikun,MA Shengli,ZHANG Liu,et al.Spatiotemporal characteristics of acoustic emission during the deformation of rock samples with compressional and extensional en-echelon fault pattern[J].Acta Seismologica Sinica,2002,24(4):385-396.(in Chinese))
[24]任利,谢和平,谢凌志,等.基于断裂力学的裂隙岩体强度分析初探[J].工程力学,2013,30(2):156-162.(REN Li,XIE Heping,XIE Lingzhi,et al.Preliminary study on strength of cracked rock specimen based on fracture mechanics[J].Engineering Mechanics,2013,30(2):156-162.(in Chinese))
[25]张国凯,李海波,夏祥,等.单轴加载条件下花岗岩声发射及波传播特性研究[J].岩石力学与工程学报,2017,36(5):1 133-1 144.(ZHANG Guokai,LI Haibo,XIA Xiang,et al.Experiment study on acoustic emission and wave propagation in granite under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(5):1 133-1 144.(in Chinese))
[26]GEIGER L.Probability method for the determination of earthquake epicenters from the arrival time only[J].Bulletin of St.Louis University,1912,8(1):56-71.