Feasibility study on mining overall height in one times of extremely close distance coal seam under complex geological conditions

The paper takes the extremely close coal seam of No.8₂ mining area of Yuandian No.1 Mine of Huaibei Mining Group as the research object.Through theoretical calculation and analysis of the critical thickness of coal seam and rock parting, the results show that the coal seams in the mining area meet the conditions of top coal caving.Through the rock mechanics test and borehole exploration, the mechanical properties and integrity of the coal seam roof are analyzed, which indicates that the roof of the lower coal seam is a weak fractured rock stratum.The discrete element numerical simulation software 3DEC is used to simulate the mining along the lower coal seam, and the caving property of the roof and top coal is analyzed.The results show that the top coal has good caving property.In addition, by analyzing the natural hazard of coal seam, the risk of coal and gas outburst, etc., it is indicated that the coal seams in the mining area have the conditions of top coal caving method.