巨厚坚硬顶板条件下断层诱冲特征及机制

Characteristics and mechanism research of coal bumps induced by faults based on extra thick and hard roof

为了揭示巨厚坚硬顶板条件下断层诱发冲击地压的前兆特征及诱冲机制,基于义马跃进煤矿25110工作面为研究对象,对某段时间内冲击现象的发生规律进行了归纳分析,针对断层诱发冲击地压的典型案例,结合微震监测数据,分析了冲击地压发生前的微震能量与频次及微震活动的时空规律,并采用数值模拟研究了采动影响下断层带附近应力场的分布特征,从地质构造、微震活动、应力场3个方面讨论了该工作面冲击地压发生的原因及机制。研究表明:巨厚坚硬顶板被F16逆断层及两正断层切割,易造成顶板大面积运动,为冲击地压的发生提供了动载条件;工作面发生冲击前微震能量与频次下降,断层带附近区域微震活动减少,有明显"缺震"现象,为冲击地压的发生积聚了能量;受采动、断层及相邻工作面采空区影响,25110工作面形成了高强度支承压力,断层带至下巷附近应力高度集中,尤其下巷底板存在较高的水平应力,为冲击地压的发生提供了力源条件。

In order to discover the precursory characteristics and the mechanism of coal bumps by faults with extra thick and hard roof, the No. 25110 working face of Yuejin Coal Mine in Yima was investigated to analyze the law of coal bumps in a certain period. The law of time and space of microseismic energy and frequency and microseismic ac- tivity were analyzed with the combination of the microseismic monitoring data based on the typical cases of coal bumps induced by faults in the condition of extra thick and hard roof. The distribution characteristics of stress fields near faults under mining influence was studied by numerical simulation. The causes and mechanism of coal bumps of the face were discussed from three aspects of geological structure, microseismic activity and stress fields. The results show the extra thick and hard roof is cut by F_16 thrust faults and two normal faults, which can cause a large roof movement, and provide a condition for the dynamic load of coal bumps. The microseismic energy and frequency decrease, and the microseismic activities near faults reduce. This is the evidence of microseism phenomenon reduction, while the energy is accumulated for coal bumps. High strength abutment pressure is formed by extraction, faults and the goaf of adjacent face. High stress concentration is formed from the faults to No. 25110 lower roadway. Especially high horizontal stress is in the floor of lower roadway. The conditions of power source are provided for coal bumps.