Change Properties of Water Conductivity Height in Coal Roof Induced by Mining in Extra Thick Coal Seams under Influence of Complex Fissures Zone

It’s a technical problem of underground mining safety to determine the water conductivity height in coal roof induced by mining under the condition of fully mechanized caving. With a number of mining engineering cases, we studied complex fault zone overlying rock mass damage characteristics under the compound effect of many mining area. The results show that overlying strata deformation and failure is the results of accumulation in mining of each mining area. Therefore, whether the overlying strata water inrush in mining process will happen or not, needs to take account of water in overlying strata in old mining area. Based on the change characteristics of water conductivity height induced by mining in seven mining areas, we built regression forecasting model, and achieved the prediction of water conductivity height induced by mining in lower coal seam, so as to provide a basis for decision-making for the safety of follow-up exploration.