干湿循环作用下弱胶结岩石声发射特征试验研究
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摘要
弱胶结岩石具有强度低、胶结弱、易风化、易水解和含水丰富等特点,针对干湿循环作用后引发工程岩体失稳的问题,通过弱胶结岩石单轴压缩试验和AE监测技术,对比分析了不同干湿循环作用次数后的岩样的变形破坏特征及破坏过程中声发射事件数、能量释放率、b值及熵值等参数的变化特征。研究结果表明:在干湿循环作用下弱胶结岩石强度劣化效应明显,弱胶结岩石到达峰值强度时轴向应变明显增加;不同干湿循环作用下弱胶结岩石破坏过程中声发射事件数和能量释放率变化趋势一致,在初始阶段较少,弹塑性阶段缓慢增加,峰值阶段达到最大值,而对于声发射b值在初始阶段相对较高,随之降低,弹塑性阶段再次升高,峰值阶段迅速降低,而峰后阶段b值依然相对较高,声发射熵值变化与b值变化恰好相反;随着干湿循环次数的增加,声发射参数的整体量发生明显变化,声发射事件数、能量释放率和熵值均随之降低,而声发射b值随之增加。在不同干湿循环次数作用条件下,弱胶结岩石破坏过程中的声发射多参数变化特征能够反映水对其宏观强度和细观结构物质的劣化作用及影响程度。
Weakly cemented granular rocks(WCGRs) normally have characteristics of low strength,weak cementation, being easily weathered and hydrolyzed. Meanwhile, WCGRs generally contain much moisture. This study focuses on the instability of engineering rock mass affected by dry-wet cycling process. Uniaxial compression tests of WCGRs and AE monitoring technique were adopted to comparatively analyze the deformation and damage characteristics of rock specimens experiencing varying dry-wet cycles. Meanwhile, the change characteristics of number of acoustic emission events(AEEs),energy release rate(ERR), b value and entropy value of AE in the rock damage process were also investigated. Results indicate that:when being subjected to dry-wet cycling process, WCGRs showed apparent deteriorating strength, and the axial strain increases at the peak strength. The number of AEEs and ERR of WCGRs under varying dry-wet cycling effects presented consistent change tendency, i.e.changing slightly in initial stage, gradually increasing when subjected to elastic-plastic deformation stage and reaching the maximum in peak stage. In contrast, the acoustic emission parameter of b value was relatively large in the initial stage, then it decreased before rising in elastic-plastic deformation stage. The b value declined rapidly in the peak stage, but it remained relatively high in post-peak stage.Changes of the AE entropy were opposite to changes of b value. With an increase in times of dry-wet cyclic process, all parameters of AE show following apparent changes: the number of AEEs, ERR and AE entropy all decreased, while the b value increased. Changing characteristics of multiple AE parameters of WCGRs corresponding to varying dry-wet cyclic processes could reveal the degradation influences of water on the rock macroscopic strength and mesoscopic structure matter, as well as the influencing degrees.
Weakly cemented granular rocks(WCGRs) normally have characteristics of low strength,weak cementation, being easily weathered and hydrolyzed. Meanwhile, WCGRs generally contain much moisture. This study focuses on the instability of engineering rock mass affected by dry-wet cycling process. Uniaxial compression tests of WCGRs and AE monitoring technique were adopted to comparatively analyze the deformation and damage characteristics of rock specimens experiencing varying dry-wet cycles. Meanwhile, the change characteristics of number of acoustic emission events(AEEs),energy release rate(ERR), b value and entropy value of AE in the rock damage process were also investigated. Results indicate that:when being subjected to dry-wet cycling process, WCGRs showed apparent deteriorating strength, and the axial strain increases at the peak strength. The number of AEEs and ERR of WCGRs under varying dry-wet cycling effects presented consistent change tendency, i.e.changing slightly in initial stage, gradually increasing when subjected to elastic-plastic deformation stage and reaching the maximum in peak stage. In contrast, the acoustic emission parameter of b value was relatively large in the initial stage, then it decreased before rising in elastic-plastic deformation stage. The b value declined rapidly in the peak stage, but it remained relatively high in post-peak stage.Changes of the AE entropy were opposite to changes of b value. With an increase in times of dry-wet cyclic process, all parameters of AE show following apparent changes: the number of AEEs, ERR and AE entropy all decreased, while the b value increased. Changing characteristics of multiple AE parameters of WCGRs corresponding to varying dry-wet cyclic processes could reveal the degradation influences of water on the rock macroscopic strength and mesoscopic structure matter, as well as the influencing degrees.
引文
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[15]许江,吴慧,陆丽丰,等.不同含水状态下砂岩剪切过程中声发射特性试验研究[J].岩石力学与工程学报,2012,31(5):914-920.XU Jiang,WU Hui,LU Lifeng,et al.Experimental research on acoustic emission rules of rock under cyclic loading[J].Rock and Soil Mechanics,2012,31(5):914-920.
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[20]王行舟,蒋长胜,洪德全,等.基于Weibull分布地震信息熵对中国大陆西部强震活动状态的分析[J].地震,2011,31(1):58-65.WANG Xingzhou,JIANG Changsheng,HONG Dequan,et al.State analysis on strong earthquake activity in West China continent based on seismic information entropy ofweibull distribution[J].Earthquake,2011,31(1):58-65.
[21]魏嘉磊,刘善军,吴立新,等.含孔岩石双轴加载过程声发射多参数特征对比分析[J].采矿与安全工程学报,2015,32(6):1017-1025.WEI Jialei,LIU Shanjun,WU Lixin,et al.Comparative analysis on different AE parameters in biaxial loading of hole rock[J].Journal of Mining&Safety Engineering,2015,32(6):1017-1025.
[2]周翠英,邓毅梅,谭祥韶,等.软岩在饱水过程中微观结构变化规律研究[J].中山大学学报(自然科学版),2003,42(4):98-102.ZHOU Cuiying,DENG Yimei,TAN Xiangshao,et al.Research on the variation regularities of microstructures in the testing of interaction between soft rocks and water[J].Acta Scientiarum Naturalium Universities Sunyatseni,2003,42(4):98-102.
[3]傅宴.干湿循环水岩相互作用下岩石劣化机理研究[D].重庆:重庆大学,2010.
[4]姚华彦,张振华,朱朝辉,等.干湿交替对砂岩力学特性影响的试验研究[J].岩土力学,2010,31(12):3704-3708,3714.YAO Huayan,ZHANG Zhenhua,ZHU Chaohui,et al.Experimental study of mechanical properties of sandstone under cyclic drying and wetting[J].Rock and Soil Mechanics,2010,31(12):3704-3708,3714.
[5]梅华,朱燕,牛传星.饱和-失水循环作用下蚀变岩劣化规律研究[J].工程地质学报,2015,23(6):1039-1044.MEI Hua,ZHU Yan,NIU Chuanxing.Laboratory study on deterioration law of altered rock under effect of water saturation-dehydration circulation[J].Journal of Engineering Geology,2015,23(6):1039-1044.
[6]秦世陶,刘蓉,杨喜华.强风化岩石长期稳定性试验研究[J].中南水力发电,2006(2):41-48.QIN Shitao,LIU Rong,YANG Xihua.Experiment study of long-term stability of strongly weathered rock[J].Central South Hydroelectric Engineering,2006(2):41-48.
[7]邓华锋.库水变幅带水-岩作用机制和作用效应研究[D].武汉:武汉大学,2010.
[8]邓华锋,李建林,王孔伟,等.“饱和-风干”循环过程中砂岩次生孔隙率变化规律研究[J].岩土力学,2012,33(2):483-488.DENG Huafeng,LI Jianlin,WANG Kongwei,et al.Research on secondary porosity changing law of sandstone under saturation-air drycycles[J].Rock and Soil Mechanics,2012,33(2):483-488.
[9]郭军,冯国瑞,郭育霞,等.饱和水煌斑岩单轴压缩力学特性变化及其微观机理[J].煤炭学报,2015,40(2):323-330.GUO Jun,FENG Guorui,GUO Yuxia,et al.Mechanical property variation under dynamic uniaxial compression and micro-mechanism of lamprophyre in saturated state[J].Journal of China Coal Society,2015,40(2):323-330.
[10]张慧梅,张蒙军,谢祥妙,等.冻融循环条件下红砂岩物理力学特性试验研究[J].太原理工大学学报,2015,46(1):69-74.ZHANG Huimei,ZHANG Mengjun,XIE Xiangmiao,et al.Experimental study of damage deterioration and mechanical properties for freezing-thawing rock[J].Journal of Taiyuan University of Technology,2015,46(1):69-74.
[11]李克钢,吴勇,郑东普.砂岩力学特性对干湿循环效应响应规律的试验研究[J].北京理工大学学报,2013,33(10):1010-1014.LI Kegang,WU Yong,ZHENG Dongpu.Mechanical behavior of sandstone and its neural network simulation of constitutive model considering cyclic drying-wetting effect[J].Transactions of Beijing Institute of Technology,2013,33(10):1010-1014.
[12]刘长武,陆士良.泥岩遇水崩解软化机制的研究[J].岩土力学,2000,21(3):28-31.LIU Changwu,LU Shiliang.Research on mechanism of mudstone degradation and softening in water[J].Rock and Soil Mechanics,2000,21(3):28-31.
[13]黄宏伟,车平.泥岩遇水软化微观机制研究[J].同济大学学报(自然科学版),2007,35(7):866-870.HUANG Hongwei,CHE Ping.Research on micromechanism of softening and argillitization of mudstone[J].Journal of Tongji University(Natural Science),2007,35(7):866-870.
[14]周翠英,朱凤贤,张磊.软岩饱水试验与软化临界现象研究[J].岩土力学,2010,31(6):1709-1715.ZHOU Cuiying,ZHU Fengxian,ZHANG Lei.Research on saturation test and softening critical phenomena of soft rocks[J].Rock and Soil Mechanics,2010,31(6):1709-1715.
[15]许江,吴慧,陆丽丰,等.不同含水状态下砂岩剪切过程中声发射特性试验研究[J].岩石力学与工程学报,2012,31(5):914-920.XU Jiang,WU Hui,LU Lifeng,et al.Experimental research on acoustic emission rules of rock under cyclic loading[J].Rock and Soil Mechanics,2012,31(5):914-920.
[16]GUTENBERG B,RICHTER C F.Frequency of earthquakes in California[J].Bulletin of The Seismological Society of America,1944,34(4):185-188.
[17]张黎明,马绍琼,任明远,等.不同围压下岩石破坏过程的声发射频率及b值特征[J].岩石力学与工程学报,2015,34(10):2057-2063.ZHANG Liming,MA Shaoqiong,REN Mingyuan,et al.Acoustic emission frequency and b value characteristics in rock failure process under various confining pressures[J].Rock and Soil Mechanics,2015,34(10):2057-2063.
[18]HARTE D.The entropy score and its uses in earthquake forecasting[J].Pure and Applied Geophysics,2005,162:1229-1253.
[19]冯利华.最大熵原理与地震频度-震级关系[J].地震地质,2003,25(2):260-265.FENG Lihua.Maximum entropy principle and seismic magnitude-frequency relation[J].Seismology and Geology,2003,25(2):260-265.
[20]王行舟,蒋长胜,洪德全,等.基于Weibull分布地震信息熵对中国大陆西部强震活动状态的分析[J].地震,2011,31(1):58-65.WANG Xingzhou,JIANG Changsheng,HONG Dequan,et al.State analysis on strong earthquake activity in West China continent based on seismic information entropy ofweibull distribution[J].Earthquake,2011,31(1):58-65.
[21]魏嘉磊,刘善军,吴立新,等.含孔岩石双轴加载过程声发射多参数特征对比分析[J].采矿与安全工程学报,2015,32(6):1017-1025.WEI Jialei,LIU Shanjun,WU Lixin,et al.Comparative analysis on different AE parameters in biaxial loading of hole rock[J].Journal of Mining&Safety Engineering,2015,32(6):1017-1025.