煤层群双重卸压开采覆岩移动及裂隙动态演化的实验研究

Experimental research on strata movement and fracture dynamic evolution of double pressure-relief mining in coal seams group

近距离煤层群双重卸压开采时,顶底板煤岩层反复破坏,形成了不同于单层煤层开采的裂隙通道,对瓦斯抽采造成了较大影响。采用相似材料模拟实验研究了单层开采和双重卸压开采覆岩位移、裂隙及应力分布与演化规律。研究表明:在双重卸压开采作用下,一些覆岩裂隙经历了生成、扩展、压实、张拉、再压实等复杂的过程;覆岩中形成了裂隙趋于闭合的"压实区"和裂隙趋于张开的"裂隙区",这些裂隙形成了立体交错的瓦斯运移通道,并随双重卸压开采工作面推进而变化。提出了近距离煤层群重复卸压开采瓦斯立体抽采模式,实现上覆煤岩层和下伏煤岩层裂隙通道瓦斯的全面抽采,并在贵州盘江精煤股份有限公司金佳煤矿成功应用。

Under the conditions of double pressure-relief mining of closed distance coal seams group,coal and rock seams in the roof and floor are destroyed repeatedly. The fracture passages formed which are different from single coal seam mining,and have important influence on gas extraction. The distribution and evolution rules of displacemeng,fracture and stress of overlying rock mass under the conditions of both single coal seam mining and double pressure-relief mining were conducted through the similar material simulation experiments. The results show that: the double pressure-relief mining results in complicate process of some of the overlying rock fracture,such as formation,extension,compaction,tension,and repeated compaction; the compacted area,where fructures are compacted,and the fructure area,where fructures are wide-open,come into being in the overlying strata. These fissures form stereo interlaced passages for gas migration,altering along with the advance of the working face. The three-dimensional drainage mode is put forward for double pressure-relief mining in the close-distance coal seams group,and gas comprehensive extraction in overlying and underlying coal seams fracture passages is obtained,with successful application in Jinjia Coal Mine of Guizhou Panjiang Refined Coal Co. Ltd.