高应力坚硬顶板深孔爆破卸压及见方效应分析

High stress hard roof deep-hole blasting pressure relief and “square” effect

高应力坚硬顶板条件下工作面推进至采空区见方,极易引起上覆岩层结构失稳,诱发顶板事故。顶板深孔爆破是高应力坚硬顶板卸压的重要手段,目前顶板深孔爆破对见方区卸压的影响研究不足。以余吾煤矿N2107工作面坚硬顶板为工程背景,开展顶板深孔爆破技术,采用微震监测、钻孔应力、钻屑监测等方法评价两次采空区见方的卸压效果。结果表明,顶板深孔爆破对坚硬顶板卸压起到积极作用,两次采空区见方期间微震监测未出现大能量事件,钻孔应力监测和钻屑监测稳定在安全值范围。采空区见方表现出见方效应的压力显现特征,局部区域微震事件能量接近预警值,钻孔应力保持上升趋势。在此基础上,提出了采空区见方的卸压优化建议,以确保及时掌握动压信息,提高卸压效果。

Under the conditions of hard roof,the working face is mined to the goaf to form a “square”,which is easy to cause the structural instability of the overlying strata and induce rock burst.Deep-hole blasting in roof is an important means to prevent rock burst.However,there is currently insufficient research on the impact of deep-hole blasting on pressure relief in the “square” areas.This study takes the hard roof of N2107 working face in Yuwu Coal Mine as the engineering background,and develops the deep-hole blasting technology for the roof.It adopts microseismic monitoring,drilling stress and drilling debris monitoring to evaluate the pressure relief effect of two goaf “square” periods.The results show that roof deep-hole blasting plays a positive role in preventing rock burst.During the two goaf “square” periods,there are no large energy events in the microseismic monitoring,and the drilling stress monitoring and drilling debris monitoring are stable within the safe range.The goaf “square” shows the pressure manifestation characteristics of the “square” effect.The energy of microseismic events in local areas approach the warning value,and the drilling stress maintaining an upward trend.We propose optimization suggestions for pressure relief in the goaf “square” to ensure timely access to dynamic pressure information and improve pressure relief effect.