孟加拉国Barapukuria矿厚煤层分层开采覆岩破坏机理

Study on the overlying rock failure mechanism of thick coal seam layered mining of Barapukuria Coal Mine in Bangladesh

孟加拉国Barapukuria矿水文地质结构复杂,矿井水害、冲击地压和采空区自燃等多种灾害并存,严重影响矿井安全生产。在分析矿井地层构造和水文地质条件基础上,开展孟巴矿厚煤层分层开采对覆岩结构影响。运用UDEC模拟不同开采高度对结构关键层破坏情况,分别计算3 m和5 m开采高度覆岩结构和垂直应力演化规律。实践表明,通过在孟巴矿应用分层开采,控制开采高度,可实现开采工作面顶板能量分次释放,有效避免应力集中,保证覆岩结构关键层的稳定性;可控制覆岩破坏范围,抑制导水裂隙带发育高度,防止LDT隔水层被击穿,有效保证底板水分次疏放。研究结果显示,孟巴矿厚煤层分层开采高度小于5 m,可满足开采后结构关键层的稳定性,降低矿井灾害影响。

The hydrogeological structure of Barapukuria mine in Bangladesh( hereinafter referred to as“Mengba Mine”) is complex,and many disasters such as mine water disaster,rock burst and goaf spontaneous combustion coexist,which seriously affects the mine safety production.Based on the analysis of mine stratum structure and hydrogeological conditions,this paper carries out the influence of layered mining of thick coal seam in Mengba Mine on overlying rock structure,uses UDEC to simulate the damage of structural key layers at different mining heights,and calculates the overlying rock structure and vertical stress evolution law at 3 m and 5 m mining heights respectively.The practice shows that by applying layered mining in Mengba Mine and controlling the mining height,the energy of the roof of the mining face can be released in several times,the stress concentration can be avoided and the stability of the key layer of overlying rock structure can be guaranteed;It can control the damage range of overlying rock,inhibit the development height of water conducting fracture zone,prevent breakdown of LDT water resisting layer,and effectively ensure the floor water drainage in several times.The research results show that the layered mining height of thick coal seam in Mengba Mine is less than 5 m,which can meet the stability of structural key layers after mining,reduce the impact of mine disasters.