Research into the reasonable offsets of the ultra-close multiple seams of coal mine

Based on the ultra-close multiple seams of coal mine,determining the reasonable offsets in type arrangement of the ultra-close multiple seams after the higher coal seam mined for more than 6.31m by theoretical analysis;using the numerical to seam roof stress distribution condition after the higher coal seam mined and the analysis of forces of the different distances between the mining roadway and coal seam edge.Determining the reasonable offsets in type arrangement of the ultra-close multiple seams after the higher coal seam mined is 6m.