硬厚岩层破断机理薄板分析及控制技术

Thin plate analysis of hard thick strata failure mechanism and its control technology

以某矿1007工作面直接顶缺失上覆硬厚砂岩岩层条件为工程背景,建立了硬厚岩层两临边固支一边简支一边自由薄板力学模型,研究了薄板应力分布特征,得到了直接顶缺失一侧采空硬厚岩层破断步距计算公式。薄板拉应力最大点在倾向固支边(x=0,y=13b/10π)处和走向固支边与自由边交角点(x=a,y=b)处,实际应力最大点位置受覆岩悬跨系数k影响。对双层硬厚砂岩岩层实施下位硬厚岩层旋转扇形深孔预裂弱化和上位硬厚岩层拉槽截断深孔爆破综合弱化技术,上位硬厚岩层运动步距降低25.7%,下位硬厚岩层实现由基本顶向直接顶的转化,降低了工作面因大面积悬露顶板突然运动引燃隅角积聚瓦斯的风险。

In view of the conditions of double hard-thick sandstone strata without immediate roof above coal seam in Working Face 1007 of one mine, an elastic thin plate model with two adjacent clamper edges, one simply supported edge, and one free edge was established as the mechanical model of hard thick strata. Stress distribution within the thin plate was then studied, and fracture step calcula-tion formula of hard thick strata was obtained. The results show that the maximum point of tensile stress is located at （x=0,y=13b/10π） of the inclination clamper edge and the intersection of strike direction clamper edge and free edge where （x=a,y=b）, while the actual position of maximum stress is affected by strata spanning modulus k. The pre-split weaken technology was carried out for the double hard-thick sandstone strata, that is, the lower hard thick stratum was weakened by fan-shaped rotation deep pre-split holes, and the upper hard thick stratum was weakened by ultramultiple-hole longhole blasting, which makes the movement step of the upper hard thick stratum decrease 25.7%, and the lower hard thick stratum changes from main roof to immediate roof. Thus, the accumulated gas ignition risk at the work face corner duo to the suddenly movement of large area hanging strata has been reduced.