不同岩性巴西劈裂试验的声发射特征  

Acoustic emission characteristics of different lithologies under Brazilian splitting

作　　者：李果[1,2] 艾婷[3] 于斌[4] 张茹[1,2] 高明忠[1,2] 徐晓炼 

机构地区：[1]四川大学水力学与山区河流开发保护国家重点实验室,四川成都610065 [2]四川大学水利水电学院,四川成都610065 [3]四川大学建筑与环境学院,四川成都610065 [4]大同煤矿集团有限责任公司,山西大同037003

出　　处：《煤炭学报》2015年第4期870-881,共12页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(51204113);国家重点基础研究发展计划(973)资助项目(2011CB201201);四川省青年基金资助项目(2012JQ0031)

摘　　要：应用声发射及其定位技术,系统研究了10种不同岩石的巴西劈裂失稳过程,分析了随应力时间变化其声发射活动规律,并从内部细观结构对其破坏机制进行了分析,得到了顶板岩层不同高度不同岩性的微观破裂机理。结果表明:由于不同岩性岩石内部微观组成存在差异,砂性岩石劈裂抗拉强度和竖直方向的压缩极限应变约为泥性岩石的1.60倍。峰值强度时,砂性岩石的振铃计数和能量远大于泥性岩石,且其振铃计数和能量时间曲线比较均匀,而泥性岩石曲线"阶跃"现象明显;岩性不同,内部初始裂纹的位置也不同,裂纹初始及其扩展方向是诱发岩样裂纹贯通的主要原因。砂性岩石破坏前兆点早于泥性岩石出现,且大部分处于不稳定裂纹扩展阶段(含粗砂细砾岩和砂岩除外);顶板岩石在受拉变形过程中,泥性岩石失稳破坏时更加剧烈和突然,预警时间较短,可能带来安全隐坏,因此必须做好相应的支护措施。By applying acoustic emission and its location technology,the authors studied the instability process of 10 different rocks in Brazilian splitting,analyzed the acoustic emission activity pattern variation with the stress and time and its failure mechanism from its internal microstructure,and obtained the microscopic fracture mechanism of different roof rock lithologies with different heights. The results show that because of the differences between the internal microscopic composition of different rocks,the splitting tensile strength and vertical direction's compressive ultimate strain of sandstone are about 1. 60 times of mudstone. At the peak intensity,the ringing counts and energy of sandstone are much larger than that of mudstone,and its ring counts-time and energy-time curves are relatively uniform. For mudstone,there is an evident 'step'phenomenon. For sandstone,a certain scale AE events generate earlier and are welldistributed. The location of the internal initial cracks changes with lithology,and the main reason for cracks through the rock sample is the initial cracks and its propagation direction. The failure precursor points of sandstone appear earlier than that of mudstone,and most of them are in an unstable crack propagation stage( except the fine conglomerate containing grit and sandstone). In the process of tensile deformation of roof rock,mudstone has a more violent and suddenfailure tendency and its warning time is short,which may cause safety risk,thus the appropriate supporting measures must be taken.

关 键 词：泥性岩石 砂性岩石 巴西劈裂 声发射 

分 类 号：TD313[矿业工程—矿井建设]