保护层开采卸压瓦斯运移及抽采技术

Pressure relief gas migration and extraction technology in protective seam mining

为了降低采煤工作面瓦斯浓度,采用保护层开采的方式对煤层进行卸压,以山西常庄矿为试验矿井,通过数值模拟对保护层开采后煤层卸压以及瓦斯运移进行研究,根据卸压和瓦斯运移特征确定了瓦斯抽采钻孔技术参数,并对抽采效果进行了检验,研究结果表明:冒落带高度为4.8m,裂隙带高度为25.2m,两侧近煤层区域裂隙发育,为裂隙发育的聚集区,形成"裂隙河";当采宽不断增大时,卸压强度增大,煤层内部应力整体呈"W"型分布;被保护层卸压分为四个区:原始压力区、压力集中区、过渡区、完全卸压区;瓦斯抽放孔最佳参数:钻孔倾角不得大于70°,封孔长度为10m,钻孔间距为30m,孔口负压为12.2k Pa;卸压瓦斯抽采浓度较卸压前大幅提高,保护层开采对于被保护层卸压起到了作用。

In order to reduce the gas concentration in coal mining face,pressure relieving of coal seam is carried out using protective seam mining. Taking Shanxi Changzhuang Coal Mine as an experimental mine, the pressure relief and gas migration of coal seam after mining under protective seam are studied by numerical simulation. According to the characteristics of pressure relief and gas migration,the technical parameters of gas drainage borehole are determined,and the extraction effect is tested. The results show that the height of caving zone is 4. 8 m, the height of fracture zone is25. 2 m. When the mining width increases, the pressure relief intensity increases, the internal stress of coal seam is distributed in a W-shape,the pressure relief zone of the protected layer is divided into four areas： original pressure area,pressure concentration area, transition zone. The optimal parameters of gas drainage hole are as follows： the angle of drilling hole must not be more than 70°,hole sealing length is 10 m,hole spacing is 30 m,hole outlet negative pressure is12. 2 k Pa,the concentration of gas extraction under pressure relief is much higher than that before release pressure,and the mining of protective seam plays an important role in unloading the pressure of protected seam.