关键词: 特厚煤层, 水力压裂, 坚硬顶煤, 弱化顶煤

Abstract: In order to effectively solve the technical problems in the design of large mining height release top coal mining in extra thick coal seam, due to the hard top coal and the working face is above the hollow area, resulting in small mineral pressure, large coal blocks in the process of coal release, poor venting, low recovery rate, etc., we adopt deep and shallow alternating borehole hydraulic fracturing technology to weaken the top coal in the extra thick hard coal seam, and conduct industrial test in Jinshan Coal 13101 working face, through FLAC3D Numerical simulation and field monitoring were used to analyze the effect of hydraulic fracturing. The results show that the hydraulic fracturing technology of alternating deep and shallow boreholes in the extra-thick hard coal seam can effectively destroy the integrity of the hard top coal seam, enable the top coal to fully collapse and recover, and shorten the cycle pressure step, reduce the working resistance of the fracturing range bracket, and the maximum size of the top coal block after fracturing drops from about 800 mm to less than 300 mm. The maximum size of the top coal block after fracturing is reduced from about 800 mm to less than 300 mm, and the recovery rate of the released top coal is increased by 11.3%, which realizes the safe and efficient production of the working face and the full recovery of resources. The technology of hydraulic fracturing to weaken the extra-thick hard top coal provides a technical way and direction for similar engineering design.