大采高开采覆岩台阶错动演化规律及突水防治

 在厚煤层大采高开采条件下，覆岩垮落带和裂隙带高度增大，岩层活动程度增强，将造成裂隙带岩层的台阶错动失稳，是开采中引发突水事故的重要条件，而裂隙带岩层的台阶错动失稳与其下位岩层的岩性结构和组合状况有关。因此，分析岩性结构对覆岩台阶错动失稳及突水防治的影响，并运用数值计算和现场实测分析的方法，研究厚煤层大采高条件下，煤层群开采煤层间不同岩性结构组合对上煤层完整性和连续性的影响规律。当煤层间岩性呈软硬岩层组合结构时，随着下位硬岩层或软岩层所占层间距比例的增大，上煤层产生的台阶错动量减小，软岩层结构比硬岩层结构更有利于减小上煤层台阶错动。给出判定台阶错动量的岩性结构构成条件，现场实测覆岩台阶错动及裂隙分布规律，提出突水防治的有效措施，保障工作面的安全生产。

EVOLUTION LAWS OF STEP OVERLYING STRATA UNDER LARGE MINING HEIGHT AND WATER INRUSH PREVENTION

In condition of thick seam and large mining height，the step instability of rock covering is caused by height of the caving zone；and fractured zone is increased and activity degree of strata is enhanced in fractured zone. Therefore，it is the important factor that causes water inrush in mining. However，the step instability of stratum in fractured zone is related to lithologic structure and combination of lower strata. Based on the important influence of lithologic structure on step instability and the water inrush prevention under large and thick seam mining height，the law that different lithologic associations among coal seams with influences on integrity and continuity of upper coal seam are studied by numerical calculation and field test. The conclusions show，when lithologic association between coal seams is soft-hard，as the proportion of lower strata to spacing of layers is higher，the step generated in upper coal seam is lower，and soft strata structure is favorable for decreasing step of upper coal seam than hard strata structure. Components of lithologic structures are put forward to determine step values；and the step and distribution law of cracks are determined. The effective measures are presented to prevent the water inrush；and safety production of working face is guaranteed.