A numerical study of the mining-induced energy redistribution in a coal seam adjacent to an extracted coal panel during longwall face mining: A case study

Mining of the coal seam adjacent to the extracted coal panel is widely practiced in China to improve coal resource recovery rates, but the energy change associated with longwall mining may present a new risk to ground stability and gateroad failure. To understand the energy change effectively, a meticulously validated numerical model, built using FLAC3D software, incorporating a double-yield model for the gob materials and a strain-softening model for the coal/rock masses, was developed to investigate the energy redistribution in coal seams and barrier pillars during the process of mining the coal seam adjacent to the extracted coal panel. The model results showed that the closer the region was to the LW 5301 gob, the higher the location and magnitude of the peak strain energy density. Consequently, the risk of rockburst in coal seams was greater than that in barrier pillars. Along the coal seam strike, with increasing advancing distance from the setup room, the magnitude of the peak strain energy density gradually increased to 1.88-2.78 times the premining energy level. In addition, along the coal seam dip, the maximum distance from the peak strain energy density to the edge of the coal seam was approximately 16-28 m, which is greater than that in the barrier pillar. The proposed numerical simulation procedure and calibrated method could be a viable alternative approach to evaluate longwall mining-induced energy changes.