坚硬顶板浅埋煤层开采地表移动特征

Surface movement characteristics of shallow coal seam mining under hard roof

针对坚硬顶板浅埋煤层开采地表出现非连续变形、易造成地面建筑物损坏的问题,以云冈矿为工程背景,采用理论分析和数值模拟的方法研究了坚硬顶板浅埋煤层开采地表移动特征。结果表明:坚硬顶板对上覆岩层起主要控制作用,覆岩随坚硬顶板发生同步变形。根据覆岩破坏、地表下沉和岩层应力分布将开采过程分为3个阶段:第一阶段为坚硬顶板破断前,地表下沉平缓,仅在坚硬顶板内部发生破坏,煤体应力集中系数随开采推进不断增大;第二阶段为坚硬顶板破断时,地表下沉急剧增加,此阶段下沉量占总量的82%,覆岩整体发生破坏,煤体应力集中系数达到最大;第三阶段为坚硬顶板破断后,随着开采的继续推进,地表最大下沉值基本稳定,下沉盆地范围增大,煤体应力集中系数开始减小。研究成果可为地质条件相似矿区的安全开采提供参考。

Aiming at the problem of surface discontinuous deformation in shallow coal seam mining under the hard roof, which is easy to cause damage to ground buildings, taking Yungang mine as the engineering background, the surface movement characteristics of shallow coal seam mining under the hard roof were studied by theoretical analysis and numerical simulation. The results show that the hard roof plays a major role in controlling the overlying rock strata, and the overlying rock strata deforms synchronously with the hard roof. According to the overburden failure, surface subsidence and stress distribution of rock strata, the mining process is divided into three stages. In the first stage, before the breakage of hard roof, the surface subsidence is gentle, with the damage only occurring inside the hard roof, and the stress concentration coefficient of the coal body increases with the mining advance. In the second stage, at the moment of hard roof breaking, the surface subsidence increases sharply, with the subsidence accounting for 82% of the total amount. The overburden rock is destroyed as a whole, and the stress concentration coefficient of coal body reaches the maximum. In the third stage, after the breakage of hard roof, with the continuous development of mining, the maximum subsidence value of the surface is basically stable, the range of subsidence basin increases, and the stress concentration coefficient of coal body begins to decrease. The research results provide a reference for the safe mining of mining areas with similar geological conditions.