近距离煤层群下保护层开采卸压保护效果研究

为了防治石屏一矿近距离煤层群开采过程中存在的煤与瓦斯突出风险,运用FLAC3D数值模拟软件分析了11025下保护层开采对上覆C19主采煤层卸压保护效果。研究结果表明:平均厚度1.3 m的下保护层开采后,距离20.9 m的上覆煤层应力释放呈现很强的分区分带性,采场中部一定范围内的应力明显降低,靠近采场边缘应力增大,中心最大位移量约为440 mm。基于法向应力和膨胀变形率指标确定煤层倾向方向卸压角运输巷侧为δ1=60.4°,风巷侧为δ2=67.9°,走向方向两端卸压角δ3=δ4=58.7°。下保护层开采后,卸压范围内C19主采煤层透气性系数提高7倍,最高瓦斯抽采速率1.13 m3/min,瓦斯压力降为0,起到了良好的卸压保护效果。

Study of Pressure Relief and Protection Effect with Lower Protective Layer Mining in Close Multiple Coal Seams

In order to prevent the coal and gas outburst risks in the mining process of close multiple coal seams in Shiping No.1 coal mine,the FLAC3 Dnumerical simulation was used to analyze the pressure relief and protect effect of 11025 lower protective layer in the overlying C19 main coal seam.The results showed that after the lower protective layer with an average thickness of 1.3 m,the stress release of the overlying coal seam with a distance of 20.9 m shows a strong zone zoning.The stress in a certain range of the central part is obviously reduced,and the stress near the edge of the stope is increased.The maximum displacement of the center is about 440 mm.Based on the normal stress and expansion deformation rate index,pressure-relief angleδ1 for coal seam tendency on the conveyance roadway side is 60.4°,while pressure-relief angleδ2 on the wind roadway side is 67.9°.Pressure-relief anglesδ3 andδ4 for coal seam strike are 58.7°on both sides.After the lower protective layer is mined,the permeability coefficient of the C19 coal seam is increased by 7 times,the maximum gas extraction rate is 1.13 m3/min,and the gas pressure is reduced to 0,which has a beneficial pressure relief and protection effect on the overlying coal seam.