以白光数字散斑相关方法作为试验的观察手段,采用双轴加载方式对一种花岗闪长岩进行直剪摩擦滑动试验,通过搭建高速数据采集系统对断层冲击地压失稳瞬态过程进行研究,观测和分析冲击失稳过程中断层位移演化时间和空间的特征。试验结果表明:(1)断层冲击地压发生与侧向压力量值有关,断层冲击地压发生需要满足一定的侧向应力条件,当侧向压力较小时,断层发生稳滑,不会发生冲击地压;(2)随着侧向压力的增加,发生断层冲击的峰值应力增加,断层冲击地压发生时的应力降增加;(3)冲击失稳过程中断层位移演化在时间上表现出间隔滑动特征,并且滑动间隔时间随着侧向压力的增加而增加,断层第一次失稳滑动的距离和滑动速度大于第二次滑动的距离和滑动速度;(4)冲击失稳过程中断层位移演化在空间上表现出滑动的差异性特征,断层不同位置处的失稳滑动量值和滑动演化特征不同,表现出断层观测点的滑动量值随着与加载端的距离增加而增加的趋势。
Characteristics of displacements evolution in aspects of time and space in instability process of fault rockburst are inspected and analyzed by using the digital speckle correlation method.The test material is a kind of Fangshan granodiorites and the specimens are loaded by a large-scale double-axis test machine;the specimen surface speckles images in instability process of fault rockburst are recorded by adopting high speed cameras.The analysis results show that:(1) Fault rockburst is associated with confining pressure.Fault rockburst needs to meet certain confining pressure conditions;and fault will slick steadily when the confining pressure is lesser.(2) Peak stress and stress drop increase in the process of fault rockburst when confining pressure increases.(3) There are interval sliding characteristics of displacement evolution in fault rockburst;and the time of interval sliding increases with the increasing of confining pressure.The sliding distance and velocity at the first sliding are both greater than that at the second sliding.(4) Fault displacement evolution displays space differences characteristics in instability process of rockburst;and sliding value will increase with the increasing of the distance between observation point and loading end.