Coal-seam inter-burden stress distribution using strip-pillar mining method

Base on the simple supported beam theory in material mechanics,the relevant mechanical model is set up when the centers of the upper pillar and lower pillar are not in a vertical direction on multi-coal seam strip mining.The impact of various geologic and mining factors(such as mining depth,seam distance,extraction ratio etc.) on the stability of strata between the coal seams is calculated and analyzed,the change laws of strata stress is studied,and gained that the seam distance and the width of lower seam is important to maintain strata stability.With the example of the mining in Fengfeng mine area,the reasonable mining width of lower seam under certain mining depth is predicted.