岩石单轴压缩下损伤表征及演化规律对比研究
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摘要
采用声波、声发射一体化装置同步测试单轴压缩下花岗岩应力应变、超声波及声发射(AE)特征演化规律,分析岩石特征应力对应的宏–细观表征,通过裂纹体积应变、声发射及声波特征等共同量化岩石损伤演化过程。结果表明:裂纹体积应变和波速对应的损伤起始应力吻合较好,AE事件、幅值分布、b值对应的应力特征值基本一致,但AE事件表征的损伤累积开始早于宏观变形和声波;初始加载阶段波速及各项异性系数K均逐渐增加,之后变化趋缓,起裂应力后侧向波速开始减小,而K逐渐增大;峰值应力前裂纹的快速聚结引起AE信号幅值大幅增加,伴随的是b值的快速下降和AE累积能量的陡增;基于起裂应力后损伤才开始累积的假定,量化并对比了裂纹体应变、AE事件等多参量表征的损伤演化规律,发现花岗岩损伤累积绝大部分发生在损伤应力之后。裂纹体应变表征的损伤具有明确物理意义,但裂纹体应变计算中泊松比选取存在一定主观性,裂纹体应变、AE能量、模量等参数表征的损伤在接近峰值应力前均出现大幅增加,与b值的快速下降对应。综合对比分析,AE能量表征的损伤具有更好的可靠性,反映了岩石损伤破裂的本质特征。
The evolution of stress-strain data, acoustic emission(AE) and ultrasonic characteristics of granite under uniaxial compression are synchronously tested by using the ultrasonic wave and AE synchronous monitoring devices. The macro-and meso-characteristics of the stress thresholds are analyzed. Also, the quantitative damage evolution of granite is inferred by the crack volumetric strain, AE parameters and ultrasonic characteristics. The results show that the crack initiation stress inferred by the crack volumetric strain and ultrasonic velocity coincides well, and the stress thresholds inferred by the AE events, AE amplitude distribution and b-value are basically identical, but the damage accumulation inferred by the AE events initially begins earlier than that by the macroscopic deformation and ultrasonic testing. At the initial loading stage, the ultrasonic velocity and velocity anisotropy coefficient K increase, and the increase rate slows down gradually. After the crack initiation stress, the lateral velocity begins to decrease, while K gradually increases. With the rapid coalescence of cracks, the amplitudes of AE signals increase significantly prior to the rock failure, accompanied by the rapid decline of b-value and dramatic increase of AE energy. Assuming that the damage accumulation begins only after the crack initiation stress, the damage evolution of granite is characterized by various parameters, such as the crack volumetric strain and AE event. It's revealed that the majority of damage occurs after the damage stress. The damage characterized by the crack volumetric strain has a clear physical meaning, but the selection of Poisson's ratio for calculating the crack volumetric strain is somewhat subjective. The damages characterized by the crack volumetric strain, AE energy and modulus all increase significantly prior to the peak stress, which coincides with the rapid decline of b-value. It's suggested that the damage estimation using the AE energy method should be preferred from the perspective of the reliability of the obtained damage values.
The evolution of stress-strain data, acoustic emission(AE) and ultrasonic characteristics of granite under uniaxial compression are synchronously tested by using the ultrasonic wave and AE synchronous monitoring devices. The macro-and meso-characteristics of the stress thresholds are analyzed. Also, the quantitative damage evolution of granite is inferred by the crack volumetric strain, AE parameters and ultrasonic characteristics. The results show that the crack initiation stress inferred by the crack volumetric strain and ultrasonic velocity coincides well, and the stress thresholds inferred by the AE events, AE amplitude distribution and b-value are basically identical, but the damage accumulation inferred by the AE events initially begins earlier than that by the macroscopic deformation and ultrasonic testing. At the initial loading stage, the ultrasonic velocity and velocity anisotropy coefficient K increase, and the increase rate slows down gradually. After the crack initiation stress, the lateral velocity begins to decrease, while K gradually increases. With the rapid coalescence of cracks, the amplitudes of AE signals increase significantly prior to the rock failure, accompanied by the rapid decline of b-value and dramatic increase of AE energy. Assuming that the damage accumulation begins only after the crack initiation stress, the damage evolution of granite is characterized by various parameters, such as the crack volumetric strain and AE event. It's revealed that the majority of damage occurs after the damage stress. The damage characterized by the crack volumetric strain has a clear physical meaning, but the selection of Poisson's ratio for calculating the crack volumetric strain is somewhat subjective. The damages characterized by the crack volumetric strain, AE energy and modulus all increase significantly prior to the peak stress, which coincides with the rapid decline of b-value. It's suggested that the damage estimation using the AE energy method should be preferred from the perspective of the reliability of the obtained damage values.
引文
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[3]MARTIN C D.Seventeenth canadian geotechnical colloquium:the effect of cohesion loss and stress path on brittle rock strength[J].Canadian Geotechnical Journal,1997,34(5):698-725.
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[7]GANNE P,VERVOORT A.Effect of stress path on pre-peak damage in rock induced by macro-compressive and-tensile stress fields[J].International Journal of Fracture,2007,144(2):77-89.
[8]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.
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[12]LOKAJí?EK T,GOEL R K,RUDAJEV V,et al.Assessment of velocity anisotropy in rocks[J].International Journal of Rock Mechanics and Mining Sciences,2013,57:142-152.
[13]LOCKNER D.The role of acoustic emission in the study of rock fracture[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1993,30(7):883-899.
[14]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.
[15]ZHANG Z,ZHANG R,XIE H,et al.Differences in the acoustic emission characteristics of rock salt compared with granite and marble during the damage evolution process[J].Environmental Earth Sciences,2015,73(11):6987-6999.
[16]TANG C A,XU X H.Evolution and propagation of material defects and kaiser effect function[J].Journal of Seismological Research,1990,13(2):203-213.
[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]刘保县,黄敬林,王泽云,等.单轴压缩煤岩损伤演化及声发射特性研究[J].岩石力学与工程学报,2009(增刊1):3234-3238.(LIU Bao-xian,HUANG Jing-lin,WANGZe-yun,et al.Study on damage evolution and acoustic emission character of coal-rock under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2009(S1):3234-3238.(in Chinese))
[19]KING M S.Elastic wave propagation in and permeability for rocks with multiple parallel fractures[J].International Journal of Rock Mechanics and Mining Sciences,2002,39(8):1033-1043.
[20]KING M S,CHAUDHRY N A,SHAKEEL A.Experimental ultrasonic velocities and permeability for sandstones with aligned cracks[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1995,32(2):155-163.
[21]PETRU?áLEK M,VILHELM J,RUDAJEV V,et al.Determination of the anisotropy of elastic waves monitored by a sparse sensor network[J].International Journal of Rock Mechanics and Mining Sciences,2013,60:208-216.
[22]CHOW T M,MEGLIS I L,YOUNG R P.Progressive microcrack development in tests on Lac du Bonnet granite:ⅡUltrasonic tomographic imaging[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1995,32(8):751-761.
[23]OUGIER-SIMONIN A,FORTIN J,GUéGUEN Y,et al.Cracks in glass under triaxial conditions[J].International Journal of Engineering Science,2011,49(1):105-121.
[24]张国凯,李海波,夏祥,等.岩石波速与损伤演化规律研究[J].岩石力学与工程学报,2015,34(11):2270-2277.(ZHANG Guo-kai,LI Hai-bo,XIA Xiang,et al.Wave velocity and damage development of rock[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(11):2270-2277.(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):1133-1144.(ZHANG Guo-kai,LI Hai-bo,XIAXiang,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):1133-1144.(in Chinese))
[26]BIENIAWSKI Z T.Mechanism of brittle fracture of rock,Parts II and III[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1985,22(6):395-430.
[27]BRACE W F,WALSH J B,FRANGOS W T.Permeability of granite under high pressure[J].Journal of Geophysical Research,2012,73(6):2225-2236.
[28]FORTIN JéR?ME,GUéGUEN YVES,SCHUBNELALEXANDRE.Effects of pore collapse and grain crushing on ultrasonic velocities and Vp/Vs[J].Journal of Geophysical Research:Solid Earth,2007,112(B8):582-596.
[29]GUTENBERG G,RICHTER C F.Seismicity of the earth and associated phenomena,Howard Tatel[J].Journal of Geophysical Research,1950,55:97.
[30]RAO M V M S,LAKSHMI K J P.Analysis of b-value and improved b-value of acoustic emissions accompanying rock fracture[J].Current Science,2005,89(9):1577-1582.
[31]LEI X L,KUSUNOSE K,RAO M V M S,et al.Quasi‐static fault growth and cracking in homogeneous brittle rock under triaxial compression using acoustic emission monitoring[J].Journal of Geophysical Research:Solid Earth,2000,105(B3):6127-6139.
[32]KACHANOV L M.Time of the rupture process under creep conditions[J].Izv Akad Nauk SSR Otd Tech Nauk,1958,8:26-31.
[33]KAWAMOTO T,ICHIKAWA Y,KYOYA T.Deformation and fracturing behaviour of discontinuous rock mass and damage mechanics theory[J].International Journal for Numerical and Analytical Methods in Geomechanics,1988,12(1):1-30.
[34]谢和平,鞠杨,黎立云,等.岩体变形破坏过程的能量机制[J].岩石力学与工程学报,2008,27(9):1729-1740.(XIE He-ping,JU Yang,LI Li-yun,et al.Energy mechanism of deformation and failure of rock masses[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(9):1729-1740.(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 Science&Geomechanics Abstracts,1994,31(6):643-659.
[3]MARTIN C D.Seventeenth canadian geotechnical colloquium:the effect of cohesion loss and stress path on brittle rock strength[J].Canadian Geotechnical Journal,1997,34(5):698-725.
[4]DIEDERICHS M S.Manuel rocha medal recipient rock fracture and collapse under low confinement conditions[J].Rock Mechanics and Rock Engineering,2003,36(5):339-381.
[5]SU K,GHOREYCHI M,CHANCHOLE S.Experimental study of damage in granite[J].Géotechnique,2000,50(3):235-241.
[6]KIM J,LEE K,CHO W,et al.A comparative evaluation of stress-strain and acoustic emission methods for quantitative damage assessments of brittle rock[J].Rock Mechanics and Rock Engineering,2015,48(2):495-508.
[7]GANNE P,VERVOORT A.Effect of stress path on pre-peak damage in rock induced by macro-compressive and-tensile stress fields[J].International Journal of Fracture,2007,144(2):77-89.
[8]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.
[9]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.
[10]曾鹏,刘阳军,纪洪广,等.单轴压缩下粗砂岩临界破坏的多频段声发射耦合判据和前兆识别特征[J].岩土工程学报,2017,39(3):509-517.(ZENG Peng,LIU Yang-jun,JIHong-guang,et al.Coupling criteria and precursor identification characteristics of multi-band acoustic emission of gritstone fracture under uniaxial compression[J].Chinese Journal of Geotechnical Engineering,2017,39(3):509-517.(in Chinese))
[11]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.
[12]LOKAJí?EK T,GOEL R K,RUDAJEV V,et al.Assessment of velocity anisotropy in rocks[J].International Journal of Rock Mechanics and Mining Sciences,2013,57:142-152.
[13]LOCKNER D.The role of acoustic emission in the study of rock fracture[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1993,30(7):883-899.
[14]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.
[15]ZHANG Z,ZHANG R,XIE H,et al.Differences in the acoustic emission characteristics of rock salt compared with granite and marble during the damage evolution process[J].Environmental Earth Sciences,2015,73(11):6987-6999.
[16]TANG C A,XU X H.Evolution and propagation of material defects and kaiser effect function[J].Journal of Seismological Research,1990,13(2):203-213.
[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]刘保县,黄敬林,王泽云,等.单轴压缩煤岩损伤演化及声发射特性研究[J].岩石力学与工程学报,2009(增刊1):3234-3238.(LIU Bao-xian,HUANG Jing-lin,WANGZe-yun,et al.Study on damage evolution and acoustic emission character of coal-rock under uniaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2009(S1):3234-3238.(in Chinese))
[19]KING M S.Elastic wave propagation in and permeability for rocks with multiple parallel fractures[J].International Journal of Rock Mechanics and Mining Sciences,2002,39(8):1033-1043.
[20]KING M S,CHAUDHRY N A,SHAKEEL A.Experimental ultrasonic velocities and permeability for sandstones with aligned cracks[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1995,32(2):155-163.
[21]PETRU?áLEK M,VILHELM J,RUDAJEV V,et al.Determination of the anisotropy of elastic waves monitored by a sparse sensor network[J].International Journal of Rock Mechanics and Mining Sciences,2013,60:208-216.
[22]CHOW T M,MEGLIS I L,YOUNG R P.Progressive microcrack development in tests on Lac du Bonnet granite:ⅡUltrasonic tomographic imaging[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1995,32(8):751-761.
[23]OUGIER-SIMONIN A,FORTIN J,GUéGUEN Y,et al.Cracks in glass under triaxial conditions[J].International Journal of Engineering Science,2011,49(1):105-121.
[24]张国凯,李海波,夏祥,等.岩石波速与损伤演化规律研究[J].岩石力学与工程学报,2015,34(11):2270-2277.(ZHANG Guo-kai,LI Hai-bo,XIA Xiang,et al.Wave velocity and damage development of rock[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(11):2270-2277.(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):1133-1144.(ZHANG Guo-kai,LI Hai-bo,XIAXiang,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):1133-1144.(in Chinese))
[26]BIENIAWSKI Z T.Mechanism of brittle fracture of rock,Parts II and III[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1985,22(6):395-430.
[27]BRACE W F,WALSH J B,FRANGOS W T.Permeability of granite under high pressure[J].Journal of Geophysical Research,2012,73(6):2225-2236.
[28]FORTIN JéR?ME,GUéGUEN YVES,SCHUBNELALEXANDRE.Effects of pore collapse and grain crushing on ultrasonic velocities and Vp/Vs[J].Journal of Geophysical Research:Solid Earth,2007,112(B8):582-596.
[29]GUTENBERG G,RICHTER C F.Seismicity of the earth and associated phenomena,Howard Tatel[J].Journal of Geophysical Research,1950,55:97.
[30]RAO M V M S,LAKSHMI K J P.Analysis of b-value and improved b-value of acoustic emissions accompanying rock fracture[J].Current Science,2005,89(9):1577-1582.
[31]LEI X L,KUSUNOSE K,RAO M V M S,et al.Quasi‐static fault growth and cracking in homogeneous brittle rock under triaxial compression using acoustic emission monitoring[J].Journal of Geophysical Research:Solid Earth,2000,105(B3):6127-6139.
[32]KACHANOV L M.Time of the rupture process under creep conditions[J].Izv Akad Nauk SSR Otd Tech Nauk,1958,8:26-31.
[33]KAWAMOTO T,ICHIKAWA Y,KYOYA T.Deformation and fracturing behaviour of discontinuous rock mass and damage mechanics theory[J].International Journal for Numerical and Analytical Methods in Geomechanics,1988,12(1):1-30.
[34]谢和平,鞠杨,黎立云,等.岩体变形破坏过程的能量机制[J].岩石力学与工程学报,2008,27(9):1729-1740.(XIE He-ping,JU Yang,LI Li-yun,et al.Energy mechanism of deformation and failure of rock masses[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(9):1729-1740.(in Chinese))