Abstract:
With the increase of mining depth and mining intensity, the problem of gas emission has become increasingly prominent, which has become a key factor restricting the safe and efficient production of coal mines. It is an important means to solve the problem of gas emission in the gob area by drilling at the top of the roof. Directional drilling has the advantages of long extraction time, good extraction effect and low extraction cost. It has become the mainstream trend of gas control in goaf of coal mine to replace high dip drilling with high directional drilling technology. In order to solve the problem of gas emission control in short distance coal seam group of high gas mine in Wuda mining area, taking the gas control in goaf of No. 9 coal seam of Huangbaici Coal Mine in Wuda mining area as the research background, the gas control technology of roof high directional drilling is applied. By means of theoretical analysis, numerical simulation and experimental investigation, on the basis of analyzing the distribution of mining fracture in overlying rock and the law of gas emission and migration under pressure relief, the coupling relationship between drilling gas extraction and the evolution of overlying rock fracture in the No.1~No.3 high level drilling field during the advance of 020913 working face in Huangbaici Coal Mine is analyzed. Therefore, the reasonable layout of high directional drilling is determined. The results show that the gas extraction concentration can be maintained at 28.17 m in the No.2 high position drilling field, which is basically the same as that at 29.22 m in the No.1 high position drilling field. When the average layer height of the drilling hole is 23.25 m, the drilling hole level is low and the gas extraction effect is not good, but the gas extraction effect is better than that of the average layer height of the drilling hole in the drilling field of No.3 high level is 13.77 m. Through comparative analysis, it is finally determined that when the vertical level of the high directional borehole in the mining face of No. 9 coal seam in Wuda Mining area is arranged in the range of 25~30 m in the roof and 10~35 m in the inclined distance from the return air lane, the borehole is in the developing range of fracture circle, and the high directional borehole in the roof can play the best extraction effect. The research results of this paper lay a solid foundation for the further popularization and application of roof directional long drilling technology in Wuda mining area.