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为了确定合理的瓦斯抽采封孔深度,建立了考虑塑性软化和扩容特性的巷道周围煤体弹塑性模型,得到了巷道周围煤体应力分布和最短封孔深度的表达式,分析了最短封孔深度的影响因素,采用钻屑量法和抽采浓度法对确定的封孔深度进行了现场验证.结果表明:初始地应力、煤体强度、支护应力和巷道尺寸是控制最短封孔深度的主要因素;埋藏深度越深,煤质越软,钻孔的封孔深度应越长;在地质构造带和大断面巷道,应加大钻孔的封孔深度;钻屑量和CH4体积分数测试结果表明,确定的封孔深度合理可靠.
In order to determine the reasonable sealing depth of gas drainage, a plastic model of the coal surrounding the roadway considering plastic softening and expansion is established. The expression of the stress distribution and the shortest sealing depth of the coal surrounding the roadway is obtained. The shortest sealing Depth of influence factors, the drilling depth method and concentration method were used to verify the depth of the sealing hole.The results show that the initial geostress, the strength of coal, the supporting stress and the size of the tunnel are the ones that control the shortest sealing depth The main factor is that the deeper the depth of burial, the softer the coal, the longer the sealing depth of the borehole should be. In the geological structure belt and large section roadway, the sealing depth of the borehole should be increased. The drill cuttings amount and the CH4 volume fraction test The results show that the determined sealing depth is reasonable and reliable.