Research on Movement and Deformation of Rock Strata between Coal Seams in Pillar Upward Mining of Left-Over Coal with Numerical Simulation Method

Based on the occurrence condition of coal seams and the geological condition on coal seam mining in Coal Mine Group Baijiazhuang, after pillar mining the 8th coal seam was well controlled, ascending mining the 6th coal seam, mining process was numerically simulated by FLAC3D,the variation law of displacements field on interlayer strata between the 6th coal seam and the 8th coal seam at different face advance were analyzed. Vertical displacement on rock strata increased gradually from below. A control stratum existed on rock strata and could play a control function for steady of strata movement, which provides a theory basis for further study on upward mining.