Abstract:
In order to clarify the pressure relief effect of the upper protective layer mining of the coal seam group on the protective layer and the influence mechanism of the remaining coal pillar on gas drainage, the No. 4, No. 8 and No. 10 coal seams of Shenzhou Coal Industry were selected for analysis. The geological conditions and mining status of the coal seams were analyzed, and the necessity and feasibility of gas drainage were clarified. Combining theoretical calculations with FLAC
3D numerical simulation, the stability of the remaining coal pillar in the mining of the protective layer and its influence range were explored. The mechanism of the stability of the coal pillar recovered from the protective layer on the pressure relief effect was analyzed. The stress response characteristics of the protected layer under the influence of the overlying coal pillar were revealed. The failure characteristics of the overlying rock of the protected layer and the formation of gas−conducting fracture channels under the influence of the coal pillar were clarified. It is determined that the stable critical width of the remaining coal pillar in the specific coal seam protective layer of Shenzhou Coal Industry is 11.2m, with the least influence occurring when the width of the coal pillar is 15m. Then, based on the simulation results, it is determined that the reasonable width of the coal pillar is not less than 17m. Within this range, it can greatly promote the development of fractures in the coal and rock masses and facilitate gas drainage. Based on the above research, different regional comprehensive gas extraction schemes (including "U" and "Y" ventilation modes) including heading face, coal seam, adjacent layers and gob are designed and implemented in 8105 working face. The results show that the drainage effect of the adjacent layer is remarkable, and the gas drainage parameters change dynamically with the advancement of the working face. This research provides key technical and theoretical support for multi−coal seam gas control, effectively ensuring the safe production of coal mines.