近距离煤层群二次采动覆岩结构演化与矿压规律

近距离煤层下部煤层开采受上部遗留煤柱影响较大，易出现应力集中、矿压显现剧烈等情况，严重威胁矿井的正常生产。本文采用数值模拟、理论分析及现场实测等方法，对极近距离煤层群二次开采时顶板结构特征、活动规律及矿压显现规律进行了研究。结果表明:下部煤层开采导致直接顶向更高更远处发展，并涵盖了上部煤层采后的直接顶及基本顶范围，形成了典型“垮落带累加”的采场覆岩结构;上部煤层开采对下部煤层起到了一定的卸压保护作用，下部煤层工作面超前支承压力峰值及影响范围减小;但上部顶板垮落压实及遗留煤柱也造成了下部煤层局部区域动压显现，对工作面回采产生不利影响。研究成果为提高资源采出率、保证生产安全提供了科学依据。

Overburden structure evolution and pressure law of second mining in close range coal seam group

The mining layout of the lower coal seam under the condition of close seam is greatly influenced by the remaining coal pillars in the upper coal seam.Thus the stress concentration and the sharp rock pressure appear frequently which seriously threaten the normal production of the mine.The roof structure characteristics,movement law and roof pressure distribution law of the lower working face were studied by numerical simulation,theoretical analysis and field measurement in this paper.The results show that the mining of the lower extra thick seam leads to the development of the direct roof to higher and farther,and covers the direct roof and the main roof range of the upper seam after mining,forming the typical overburden structure of the stope with super large mining space,which is “super long distance and super large damage height”.Mining of the upper seam plays a certain pressure relief protection to the lower seam.As a result,the peak value and influence range of the advanced abutment pressure in the lower coal seam face are reduced,but the caving and compaction of the upper roof and the remaining coal pillars cause the local dynamic pressure manifestation in the lower coal seam,which has a negative impact on the mining of the working face.The research results provide a scientific basis for improving resource recovery rate and ensuring production safety.