关键词: 被保护层开采, 煤柱留设, 支承压力, 应力分布, 瓦斯突出分区防治

Abstract: In order to explore the influence law of coal pillar on the evolution characteristics of mining stress for the protected layer in the process of coal seam group mining, the FLAC3D strain softening model is used to simulate the evolution law of support pressure and three-dimensional stress in the mining of the protected layer under the influence of coal pillar. The results show that the working face of the protected layer is in the state of pressure relief except for the coal pillar influence area. The evolution law of abutment stress is closely related to the mining progress of the protected layer. When the advancing position of working face is in the influence area of coal pillar, the abutment stress suddenly increases to 1.25 times of the original rock stress, and the curve shows a rapid rising trend. The higher the horizon is from the protective layer, the smaller the vertical stress value is. When the horizon distance is greater than 26 m, the three-dimensional stress distribution is basically no longer affected by the coal pillar. Under the influence of coal pillar, the working face of the protected layer can be divided into three parts: coal pillar influence area, coal pillar influence expanding area and pressure relief area. At the same time, the comprehensive measures of high-level through layer drilling, gas drainage by buried pipe in goaf, mesh through layer drilling and large-diameter pressure relief drilling were implemented in the working face. The total gas drainage is more than 90 days, and the gas drainage is 64805 m3. The effect inspection indexes are not over limit, and the safe mining is realized.