关键词: 近距离煤层群, 保护层开采, 卸压范围, 渗透性系数, 抽采效果

Abstract: Aiming at the problem of gas prevention and control in the mining of short distance coal seam group in Shaqu mine, the paper comprehensively uses the method of theoretical analysis and numerical simulation to analyze the effect of floor pressure relief during the mining of protective layer, and compiles fish language in combination with the development form of plastic zone to obtain the variation law of permeability coefficient in the protected layer, which is used in engineering practice. The results show that when No.2 coal seam is mined as the protective layer, the pressure relief depth of the floor can reach 20-36m, which is greater than the maximum vertical distance between No.3 + 4 coal seam and No.3 coal seam, and No.3 + 4 coal seam is within the protective range of the upper coal seam. With the exploitation of the protective layer, the permeability coefficient of the protected layer is significantly increased, and the maximum value can reach 5.2. Although the permeability coefficient will fall down with the advancing of the working face, it is still greatly improved compared with the initial value. In the mining of No.2 coal seam, the gas concentration in the bottom through layer drilling is measured. The maximum gas concentration in the drilling hole can reach 70%, and the extraction effect is good.