矿震诱发型冲击地压临场预警机制及应用研究

STUDY OF SITE FOREWARN MECHANISM OF ROCK BURST INDUCED BY SHOCK BUMP AND ITS APPLICATION

矿震诱发型冲击地压预警是世界性难题,通过多年的监测预警机制研究和现场实测发现,采场监测区域内应力突降是此类型冲击地压的典型前兆之一。结合关键岩层断裂特征与煤岩体应力变化关系,得出依据矿震发生前煤岩应力突变规律实现临场预警的机制:高位关键岩层拉伸断裂前后采场超前应力从单峰演化为双峰状态,在关键岩层断裂位置下方煤岩体内出现应力突降,数分钟后因岩梁断裂回转,其下方支承区域内岩体受强烈动载破坏而引发矿震。根据临场应力突降值和突降范围,判定矿震对采场的危害程度和影响范围,进而及时作出现场避灾处理,结合开采前预判关键层破断步距和开采过程中高精度微震追踪岩层破裂高度,判断矿震发生的区域,提高临场预警的时效性和准确性。本文揭示的现象和关键数据为临场预警矿震诱发型冲击地压提供了一种直观有效的方法。

Forewarning of rock burst induced by shock bump is a worldwide problem. Long-term spot monitoring and study on the mechanism of monitoring and forewarning shows that the sudden decrease of stress in the stope monitoring area is a precursor to this kind of rock burst. We can obtain the mechanism of spot forewaring based on the stress drop in coal and rock mass before shock bump occurred by analyzing the inner relationship between fracture characteristics of the key stratum triggering shock bump and variation laws of stress in coal and rock mass. The mechanism is that advanced abutment pressure evolves from single peak to double peaks before and after the tensile fracture of the overlying key stratum,and stress drop occurs in the coal and rock mass beneath the fracture position of the key stratum. After that about a few minutes,the strong dynamic load induced by rock beam rotation and fracture leads to rock mass destruction and shock bump in the below loading area. According to the drop value of spot stress and its variation range,the damage extent and influence scope of shock bump can be determined,and thus spot control measures can be adopted timely. Combined with predicting breaking span of the key stratum before mining,tracking rock fracture height by high-precision microseismic monitoring technology can estimate the danger area where shock bump will happen. This whole prediction method will enhance the time-effectiveness and accuracy of spot forecast. The phenomena and critical data revealed in this paper provide a direct and effective approach to the spot forewarning for rock burst induced by shock bump.