浅埋煤层坚硬直接顶破断诱发冲击地压机理及防治

Mechanism and prevention of rock-burst induced by immediate roof breakage in shallow-buried coal seam

针对浅埋缓倾斜煤层坚硬直接顶下回采工作面冲击地压问题,采用微震及矿压监测方法确定了坚硬直接顶超前工作面破断的位置及顶板周期来压步距,在此基础上分析了回采工作面冲击地压的能量来源和致灾机理,建立了坚硬直接顶超前工作面破断的力学模型,推导了直接顶初次破断和周期破断的步距公式并计算得到了直接顶超前工作面的破断距离。结果表明,直接顶的周期破断步距以及破断产生的矿震能量均比基本顶周期来压步距及矿震能量小,但由于直接顶距离煤层近以及直接顶超前工作面破断位置距离煤壁过小,坚硬直接顶的周期破断引起的动载增大了工作面冲击地压危险。据此确定了在巷道进行直接顶预裂爆破以增大直接顶超前工作面煤壁破断距离的冲击地压治理措施,微震监测结果显示超前预裂爆破有效降低了工作面冲击地压危险。

In order to prevent rock-burst occurring under the hard immediate roof of shallow-buried softly-inclined coal seam,micro-seismic and underground pressure monitoring equipment were used to identify the breakage location of hard immediate roof and the periodical weighting paces of basic roof. Based on the data above,rock-burst energy source and disaster-causing mechanism was analyzed,a mechanics model of immediate roof breakage was set up,the first and periodical breakage pace formula of immediate roof were deduced and the distance between breakage location and coal wall of face was calculated. The study results show that although the breakage pace and energy of immediate roof were minor than those of basic roof,the dynamic load induced by the periodical breakage of immediate roof could increase rock-burst danger in mining face. Therefore,pre-blasting immediate roof in roadways was applied to reduce the distance between breakage location and coal wall of face and decrease rock-burst danger degree,which was demonstrated by micro-seismic monitoring data.