煤层群保护层卸压强化抽采应力—渗流规律研究

Research on stress and seepage law of pressure relief and enhanced extraction in coal seam group protection layer

为研究煤层群保护层开采及瓦斯抽采影响下的煤层瓦斯运移规律,构建了开采扰动影响下的煤体、岩体渗透率模型,并通过试验进行验证。结合张集煤矿地质条件,运用多物理场耦合模拟软件COMSOL,模拟得到煤层群保护层开采期间采场的卸压增透规律、瓦斯运移规律,以及钻孔不同抽采时间的采场瓦斯含量变化。研究结果表明,8煤作为保护层开采,随着工作面的推进,被保护层卸压范围和卸压程度逐渐增大,4煤层、6煤层最大应力卸压程度分别为27.8%、42.6%,对于6煤层的卸压效果最好;随着工作面推进,采区的瓦斯渗流场范围和渗流速度均增大,瓦斯向8煤层采空区方向涌出;通过保护层开采卸压结合穿层钻孔抽采,提高了瓦斯抽采效率,降低了煤层瓦斯含量,有效降低了煤与瓦斯突出危险性。

To study the migration law of coal seam gas under the influence of coal seam protection layer mining and gas extraction,a model of coal and rock mass permeability considering the influence of mining disturbance was constructed,and tests were verified.Combining the geological conditions of Zhangji Coal Mine,the multiphysics coupling software COMSOL was used to simulate the pressure relief and permeability enhancement laws and gas movement law of the stope during the mining of the protective layer,as well as the change of stope gas content under different extraction times under drilling and extraction conditions.The results showed that the No.8 coal seam was mined as a protective layer,with the advancement of the working face,the range of pressure relief and the degree of pressure relief of the protective layer gradually increased,the maximum pressure relief degrees of the No.4 and No.6 coal seams were 27.8%and 42.6%,respectively,and the best relief effect was achieved for No.6 coal seam,which had the best pressure relief effect for No.6 coal seam.With the advancement of the working face,the gas seepage field range and seepage velocity in the mining area both increased,and the gas gushed out in the direction of the No.8 coal seam goaf.Through the protective layer mining and pressure relief combined with through-layer drilling extraction,the gas extraction efficiency was improved,the coal seam gas content was reduced,and the risk of coal and gas outburst was effectively reduced.