防隔水煤柱切顶卸压定向爆破参数设计及工程应用

Parameters design and engineering application of directional blasting forroof cutting pressure relief of waterproof coal pillar

针对煤矿井下紧邻断层的防隔水煤柱稳定性保护问题,以鹤壁中泰矿业3309工作面防隔水煤柱为工程背景,对防隔水煤柱切顶卸压定向爆破参数设计及工程应用进行研究。通过对切顶卸压前后防隔水煤柱支撑压力分布进行对比分析,揭示了切顶卸压定向爆破作用机理,采空区顶板垮断时大悬臂结构被切断进而迅速垮落,防隔水煤柱上方侧向支撑压力缓慢上升然后延伸至深处缓慢下降到原岩应力。利用FLAC3D和ANSYS/LS-DYNA软件建立不同不耦合系数定向聚能爆破模型,数值模拟结果显示,切顶卸压后应力峰值降低了约27.8%,且峰值位置与3309工作面煤柱帮的距离明显增大,改善了3309工作面回风巷道附近区域应力环境;综合考虑切缝效果和炸药利用率,确定了不耦合系数1.7为正常段最优装药结构;根据数值分析结果和断层分布情况对3309工作面回风巷道进行系统性差异化爆破参数设计,现场应用表明切顶卸压定向爆破效果良好,对防隔水煤柱的保护起到了有效的作用。

Aiming at the stability protection of the waterproof coal pillar adjacent to the fault in the coal mine,the design and application of directional blasting parameters was studied for the roof cutting pressure relief of waterproof coal pillar,with the engineering background of the 3309 working face in Hebi Zhongtai Mining Industry.By comparing and analyzing the support pressure distribution of the waterproof coal pillar before and after the roof cutting,the mechanism of directional blasting was revealed.When the roof of the goaf collapses,the large cantilever structure is cut off and then collapses rapidly,and the lateral support pressure above the waterproof coal pillar rises slowly,and then extends to the depths and slowly decreases to the in-situ stress.FLAC3D and ANSYS/LS-DYNA software were used to establish different uncoupling coefficient directional energy blasting models,and the numerical simulation results showed that the peak stress after roof cutting was reduced by about 27.8%,and the distance between the peak position and the coal pillar rib of the 3309 working face was obviously increased,which improved the stress environment of the area near the working face air return way.Comprehensively considering the slitting effect and explosives utilization rate,the optimal charging structure of the normal section was determined by the uncoupling coefficient of 1.7;according to the results of numerical analysis and the distribution of faults,systematic differentiated blasting parameter design was carried out for the air return way of the 3309 working face,and the field application showed that the effect of directional blasting was favorable for the roof cutting pressure relief,which was effective to protect the waterproof coal pillar.