重复采动影响下含瓦斯岩层瓦斯运移规律
Gas migration law of gas-bearing rock strata under the influence of repeated mining
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摘要: 受重复采动影响, 煤层邻近岩层中赋存的瓦斯解吸涌出, 成为工作面瓦斯主要来源之一。为研究重复采动影响下含瓦斯岩层中瓦斯运移规律, 以沙曲一矿5#煤及其邻近煤岩层为工程背景, 在测定煤岩体瓦斯基础参数的基础上, 通过数值模拟研究了重复采动影响下煤岩体卸压增透范围, 得到了含瓦斯岩层渗透率的空间分布情况, 进而对含瓦斯岩层瓦斯运移规律进行模拟。研究结果表明: 邻近岩层中, L5灰岩层瓦斯赋存量最高, 含量约为5#煤层的14.3%;重复采动导致煤岩体卸压程度增大, L5灰岩层卸压区分布在永久煤柱的边缘区;L5灰岩层卸压区内渗透率最高可达4.8×10-15 m2, 为初始渗透率的7.7倍, 高渗区域与卸压区域分布一致;L5灰岩层内赋存的瓦斯解吸并上涌至工作面, 致使上隅角瓦斯浓度由6.1%升高至7.1%;受巷道通风影响, L5灰岩层瓦斯主要聚积在岩层后方与回风巷侧, 是瓦斯抽采时应关注的重点区域。Abstract: Under the influence of repeated mining, the gas endowed in the rock strata adjacent to the coal seam desorbs and gushes out, becoming one of the gas sources in the working face.In order to study the gas migration law of gas-bearing rock strata under the influence of repeated mining, the No.5 coal seam in Shaqu No.1 Coal Mine and its adjacent coal rock layers were taken as the engineering background.On the basis of measuring the basic parameters of gas in coal and rock mass, numerical simulation was used to study the range of pressure relief and antireflection of coal and rock mass under the influence of repeated mining, and the spatial distribution of the permeability of gas-bearing rock strata was obtained, then the gas migration law of gas-bearing rock strata was simulated.The research results show that the L5 limestone strata has the highest gas occurrence among the adjacent strata, and the gas content is about 14.3% of the No.5 coal seam. Repeated mining leads to increased pressure relief degree of coal and rock mass, and the pressure relief area of L5 limestone strata is distributed in the edge area of permanent coal pillar.The maximum permeability in the pressure relief area of the L5 limestone strata can reach 4.8×10-15 m2, which is 7.7 times of the initial permeability.The distribution of the high permeability area is consistent with the pressure relief area.The gas in L5 limestone strata is desorbed and gushed up to the working face, resulting in the gas concentration in the upper corner rising from 6.1% to 7.1%.Influenced by the roadway ventilation, the gas in L5 limestone strata mainly gathers in the back of the rock layer and the side of the return airway, which is the key area that should be paid attention to during gas extraction.