神东矿区近距离煤层出一侧采空煤柱压架机制

MECHANISM OF SUPPORT CRUSHING WHILE MINING OUT OF UPPER GOAF-SIDE COAL PILLAR IN CLOSE DISTANCE SEAMS OF SHENDONG MINING AREA

针对神东矿区石圪台煤矿1-2煤一盘区多个工作面在推出上覆1-2上煤一侧采空煤柱过程中发生的压架事故,采用现场实测、理论分析和模拟试验,对压架发生的机制及其防治对策进行研究。结果表明:下煤层切眼布置于上覆煤柱区下方,造成工作面回采期间经历由煤柱区进入采空区下的开采过程,即为出一侧采空煤柱的开采。在此过程中出现的压架存在2种类型,当切眼距煤柱边界较远而大于煤柱上方关键层的初次破断距时,则出煤柱时该关键层将处于周期破断状态,并与煤柱边界采空区一侧已断块体形成非稳定的三铰式结构,该结构的相对回转运动传递的过大载荷是压架发生的根本原因。当切眼距煤柱边界较近而介于煤柱上方关键层的初次破断距和周期破断距之间时,则出煤柱时该关键层将呈现悬臂式破断,由于其破断跨度较大,将造成支架载荷的过大而压架;同时,若此破断跨度超过该关键层1.7～1.9倍的周期破断距时,其压架强度将明显增高。模拟试验和工程实践表明,缩小下煤层切眼距煤柱边界的距离使得煤柱上方关键层不发生破断,可有效防治出一侧采空煤柱开采的压架。

Aiming at the support crushing accidents during the faces mining out of the upper 1.2 goaf-side coal pillar in panel of coal seam 1-2 of Shigetai coal mine, the mechanism and its prevention measures are researched based on the field measurement, simulation experiments and theoretical analysis. The results show that when the cut-hole of the lower seam was set under the upper coal pillar, the working face would go through the mining stage from the area under the coal pillar to that under the goaf, which was called the mining out of the upper goaf-side coal pillar. In the mining process, two situations exist in the support crushing by the influence of the cut-hole position. If the distance between the cut-hole and the upper coal pillar boundary is larger than the first breaking step of the key stratum（KS） above the pillar, the periodic breaking block of the KS and its broken block at the side of goaf near the pillar boundary will form an unstable three hinged structure when mining out of thepillar; and the excessive load caused by the relative rotary motion of the structure is the fundamental source for the support crushing. If the distance is between the first breaking and periodic breaking step of the KS, the KS will present the cantilevered breaking state when mining out of the pillar; and the support crushing is caused by the excessive load due to its long breaking span. Meanwhile, when the KS breaking span is more than 1.7 - 1.9 times the length of its periodic broken step, the risk level of the support crushing will be obviously higher than that in the former situation. The simulation experiments and engineering practices show that the support crushing accident during the mining out of the upper goaf-side coal pillar can be effectively controlled by reducing the distance between the cut-hole and coal pillar boundary, so as to prevent the breaking of the KS above the pillar.