深部采动断层异变的强制逆冲机制

FORCED THRUST MECHANISM OF FAULT MUTATION IN DEEP MINING

在老虎台矿,发现深部开采过程正断层活化异变为逆冲断层运动,灾变为强矿震能量释放。应用微震监测和震源机制解答技术,结合现场调查、地应力测量和三维数值试验,探索这种现象的力学机制。分析得出:煤矿采动导致断层活化,断层的运动方式受采动应力作用方式主导,可以改变原生断层的破裂机制;深部正断层从下盘跨越断层后在上盘开采,采动集中应力导致正断层改变运动方向,发生采动强制逆冲运动,灾变为强矿震能量释放,并可剪断凸凹体和障碍体,发生双震型矿震;开采过程应根据采动应力作用的方式,动态确定防范正断层灾变的内容;装备高精度微震设备,跟踪分析岩体破裂源空间分布和破裂机制,可早期发现采动断层活化及异变动向,提早采取防范措施。

In Laohutai coal mine,it occurred that normal fault was activated and varied into thrust fault movement,and strong mining earthquake energy release was produced during deep mining. The mechanical mechanism was explored by using microseismic monitoring and focal mechanism solutions,combining field investigation,in-situ stress measurement and three-dimensional numerical experiments. Analysis and conclusions： coal mining resulted in activation of faults,and the action mode of mining stress led the mode of fault movement. changing the fracture mechanisms of original fault;deep normal fault was mined in hanging wall after crossing fault in footwall,and the change of the direction of normal fault motion was caused by mining induced concentrated stress,forcing thrust motion,accompanied by the releasing of strong mining earthquake energy,and barriers and asperities can be sheared,also it may initiate second main-earthquake;the details about preventing normal fault catastrophe should be dynamically determined,according to the mode of action of stress during mining;by equipping with high-precision microseismic equipment,tracing analysis on spatial distribution of rock rupture sources and failure mechanism,the tendency of mining induced fault activation and variation can be caught out ahead of time,so that precaution will be taken promptly.