基于热流固耦合工作面前方瓦斯渗流数值模拟

通过分析温度和地应力对深部煤体瓦斯运移规律的影响，建立了瓦斯渗流热流固耦合模型，以贵州省松和煤矿15#煤层12150采煤工作面为例，利用ComsolMultiphysics软件对深部煤层工作面前方瓦斯渗流进行数值模拟。研究结果表明:受采动影响，在工作面前方“三带”中，卸压区存在大量新裂隙和通道，瓦斯压力梯度最大；在应力集中区至卸压区过渡段瓦斯压力下降速度最快，解释了在该区容易导致瓦斯突出的原因；在应力集中区，瓦斯压力和有效应力较高，压缩煤体，导致煤颗粒排列紧密，渗透率降低；在卸压区，煤体体积形变逐渐变大，产生了很多新裂隙，发生扩容，渗流通道贯通，导致渗透率急剧增加，因此在应力最大处形成了煤层渗透率最低点，随着时间的推移，渗透率最低点逐步远离工作面；在采煤工作面前方，虽然温度升高后瓦斯热运动加剧，有促进瓦斯渗透率的趋势，但由于工作面前方有效应力较大，煤体受热膨胀应力小于有效应力，导致煤体内膨胀，渗流空间减小，造成渗透率降低。

Numerical simulation on gas seepage in front of working face based on fluid-solid-heat coupling

Through analyzing the influence of temperature and ground stress on the gas migration laws of deep coal body, a fluid-solid-heat coupling model of gas seepage was established, and taking the 12150 coal mining face in 15# coal seam of Songhe Coal Mine in Guizhou province as example, the numerical simulation on the gas seepage in front of the working face of deep coal seam was carried out by using the ComsolMultiphysics software. The results showed that due to the influence of mining activities, there existed a large amount of new fissures and channels at the pressure relief area in the "three zones" in front of the working face, and the gas pressure gradient was the largest. The drop speed of gas pressure in the transition section from the stress concentration area to the pressure relief area was the fastest, which explained the reason that the gas outburst was easily to occur in this area. In the stress concentration area, the gas pressure and the effective stress were high, and the coal body was compressed, which leaded to the close arrangement of the coal particles and the decrease of the permeability. In the pressure relief area, the volume deformation of the coal body became larger gradually, resulting in a lot of new fissures, the volume expansion occurred, the seepage channels connected, leading to the sharp increase of permeability, so the lowest point of coal seam permeability formed at the position with the maximum stress, and with the passage of time, the lowest point of permeability gradually went away from the working face. In front of the coal mining face, though the thermal motion of gas aggravated after the increase of temperature, which tended to promote the gas permeability, however, due to the large effective stress in front of the working face, the thermal expansion stress of the coal body was smaller than the effective stress, causing the expansion in the coal body, then the seepage space reduced, and the permeability decreased.