Abstract The repeated mining of deep adjacent coal seam group with high gas has great influence on strata behaviours and dynamic disasters in underground mining. In this paper, the movement of overlying strata and gas for bi-level mining are studied, and then the effective methods of prevention and control disasters with consideration to the ‘time-space-strength’ is put forward. The results show that after the completely mining of upper coal seam and the lower coal seam been mining, the layers between coal seams move substantially and the tensile stress increases significantly, resulting in the overlying rock fissures are connected. Then, the stress of lower coal seam reaches peak value, and the dominant gas flow channel is formed, thereby causing in strong dynamic pressure phenomena such as increase in the gas pressure. After this, the self-developed gas sealing flexible air bag is used to block the gas in the position of face corner and to drain the gas in the goaf, which can effectively prevent gas outburst. The study results are of great significance and provide guidance to prevent dynamic disasters (i.e. gas outburst) caused by the repeated mining of adjacent coal seams.

中文翻译：

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深相邻高瓦斯煤层群下覆岩运动规律及动力灾害防治措施

摘要 深部相邻高瓦斯煤层群的重复开采对地下开采的地层行为和动力灾害影响很大。本文对双层开采上覆地层和瓦斯的运动进行了研究，提出了综合考虑“时空强度”的灾害防治方法。结果表明，上煤层和下煤层开采完毕后，煤层间的层间移动明显，拉应力显着增加，导致上覆岩裂缝连通。然后，下部煤层应力达到峰值，形成主导瓦斯流道，从而引起瓦斯压力升高等强烈动压现象。在这之后，采用自主研发的气封柔性气囊，用于封堵工作面角部瓦斯，并排出采空区瓦斯，可有效防止瓦斯突出。研究结果对防止相邻煤层重复开采引起的动力灾害（即瓦斯突出）具有重要意义和指导意义。