特厚煤层大空间综放采场覆岩运动及其来压规律研究

Overlying strata movement law and its strata pressure mechanism in fully mechanized top-coal caving workface with large space

为实现复杂条件下特厚煤层综放工作面安全高效开采,采用理论分析、相似模拟试验和微震监测等多种方法,对极近距采空区下特厚煤层综放采场大空间覆岩结构形式及其运动规律和覆岩来压机理进行研究。结果表明:1)上部2^#煤层的开采,从下向上的上覆岩层依次发生垮落、断裂和弯曲下沉运动,上覆岩层完整性得到破坏,且不易积聚弹性能,降低了下部极近距离特厚煤层综放工作面顶板动压系数和来压强度;2)考虑上部煤层的采动影响,在特厚煤层综放采场,上覆岩层下沉运动空间大,采动围岩超前破坏范围大,基本顶岩梁岩块数量多于一般综放采场,且其下沉运动主要为回转失稳或剪切滑落失稳,采场覆岩动压发生的可能性降低;3)相似模拟试验、微震监测和现场实测等结果与理论分析基本吻合,特厚煤层综放采场覆岩超前远距离破坏范围达400 m;4)支架工作阻力和现场矿压实测结果表明,支架工作状态较稳定,来压动载系数平均1.19~1.22,支架来压步距离散性较大、规律性不强,工作面整体来压强度较小。结果可为类似条件下特厚煤层综放工作面支架选型、顶板控制、高效生产等提供参考。

To realize safe and efficient mining of fully mechanized top coal caving mining workface in the extra-thick coal seam under complicated conditions, the structure form and movement law of large space overburden strata and its strata pressure mechanism of fully mechanized top-coal caving stope under extra-thick coal seam in extremely close goaf have been analyzed through theoretical analysis, similar simulation test and field monitoring. The results have shown that: 1) In the mining of the upper 2^# coal seam, collapse, fracture and bending subsidence occur successively in the overlying strata from the bottom upward, resulting in the destruction of the integrity of the overlying higher strata and the difficulty in accumulating elastic energy, which reduces the dynamic pressure coefficient and pressure strength of the roof of the full mechanized top-coal caving face with extremely close goaf in the working face;2) In the fully mechanized top-coal caving mining face with extra-thick seam, considering the effect of mining in the upper coal seam, the overlying rock has a large space for subsidence movement and the surrounding rock has a large range of advanced failure, and the number of beam blocks in the old roof is more than that of the general fully-mechanized top-coal caving stope, and the subsidence movement of overlying main roof strata is mainly rotation instability or shear sliding instability, which reduces the possibility of forming dynamic load pressure on the support of working face;3) The results of similarity simulation experiment, microseismic monitoring and field measurement basically coincide with the theoretical analysis, with the advanced remote failure range of overlying strata in fully mechanized top-coal caving of extra thick coal being up to 400 m;4) The supporting work resistance and the field ore pressure results show that the support working state is stable, with the dynamic load coefficient being 1.19-1.22 on average, and moreover, the whole strata pressure intensity is small, the distance dispersion of the support is large and the regularity is not strong. The results can provide reference for support selection, roof control, and high efficiency production of fully mechanized caving mining workface in extra-thick seam under similar conditions.