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平顶山天安煤业股份有限公司十二矿己15-31010工作面垂深为1 015～1 130 m,为煤与瓦斯突出煤层,采用开采解放层己14煤层预抽瓦斯是解决己15煤层煤与瓦斯突出的关键技术,因此,针对深部保护层开采过程中下部煤层的卸压效果需进行深入分析。首先根据实际地质条件建立了三维数值模型,计算了己14煤开采过程中下部己15煤层的应力分布。计算结果显示,下部己15煤层在上部保护层开采过程中压力先升高后降低,在采面通过40 m后煤层压力降低至小于1 MPa;但在采空区外侧集中应力区,最大应力值高达42 MPa。现场监测数据显示,采空区下方煤层巷道瓦斯浓度显著增大,但外侧煤层巷道瓦斯浓度变化较小,在上方采面通过40 m后,巷道变形趋于稳定,煤层得到充分卸压。综合数值计算结果和现场监测数据可知,深部近距离保护层开采可以显著降低下部煤层压力,释放煤层瓦斯,但由于集中应力的影响,难以释放位于采空区边缘的下部煤层瓦斯。
Pingdingshan Tianan Coal Mining Co., Ltd. 12 mine has 15-11010 working face down to 1 015 ~ 1 130 m, for the coal and gas outburst of coal seam, Gas outburst of the key technologies, therefore, for the deep protection of the mining process of the lower seam pressure relief effect needs further analysis. Firstly, based on the actual geological conditions, a three-dimensional numerical model was established and the stress distribution in the lower part of coal seam 15 was calculated. The results show that the pressure in the lower part of 15 coal seam increases first and then decreases in the process of upper protective layer mining. The pressure in the coal seam decreases to less than 1 MPa after 40 m passes the mining face; however, in the concentrated area outside the goaf, the maximum stress Up to 42 MPa. The on-site monitoring data showed that the gas concentration in the coal seam roadway under the goaf increased significantly, but the gas concentration in the outside coal seam roadway changed little. After the upper mining face passed through 40m, the roadway deformation tended to be stable and the coal seam was fully decompressed. According to the comprehensive numerical results and on-site monitoring data, it can be seen that the mining of the deep short-range protective layer can significantly reduce the pressure of the lower coal seam and release the coal seam gas. However, due to the concentrated stress, it is difficult to release the lower coal seam gas located at the edge of the goaf.