Research on the Relief Effect of Coal and Rock in The Protected Layer Under the Mining Action of The Upper Protective Layer

Abstract

In order to investigate the pressure relief effect of coal and rock in the protected layer during long-distance upper protective layer mining, the FLAC3D numerical simulation software was used to simulate and analyze the deformation and stress changes of the coal and rock layers after upper protective layer mining, and the pressure relief range was verified through on-site drilling. The research results show that: (1) After the mining of the protective layer of the 7 # coal seam, the maximum upward deformation of the roof of the 12 # coal seam can reach 40mm, and the maximum upward deformation of the floor of the 13 # coal seam can reach 35mm. (2) At the middle position of the 13 # coal seam floor, the vertical stress decreased to 2.5MPa, which is 15MPa lower than the original stress. (3) The on-site pressure measurement drilling proved that the mining of the protective layer of the 7 # coal seam had a certain pressure relief effect on the overlying 12 # and 13 # coal seams.