煤巷掘进过程煤层瓦斯运移规律的数值模拟

Numerical simulation on gas migration law during tunnel excavation in thick coal seam

研究煤巷掘进过程中瓦斯运移规律对瓦斯灾害防治具有重要的意义.本文构建了瓦斯流动的固气耦合模型,应用RFPA_GASFLOW软件对煤巷掘进过程瓦斯运移进行数值模拟.研究表明,煤巷掘进过程中,掘进巷道周围产生瓦斯渗流场,瓦斯压力梯度等值线呈轴对称分布并随着巷道的掘进向前移动;掘进工作面前方和掘进巷道两帮煤壁内的瓦斯压力的变化规律相同,瓦斯压力在渗流场内呈抛物线分布,瓦斯压力梯度在巷道附近最大,并逐渐增加至煤层初始瓦斯压力,采掘作业只对巷道周围一定范围内的瓦斯压力有影响;随着煤壁暴露时间的增加,巷道周围煤层中的瓦斯压力和瓦斯流量逐渐降低,最终趋于稳定.

The study of gas migration law during tunnel excavation in thick coal seam is of important significance for preventing gas disasters.A coupling model between coal and gas is constructed,and then gas migration law during tunnel excavation in thick coal seam is simulated by means of RFPA software.Results show that the gas seepage field appears around the roadway during tunnel excavation in thick coal seam,gas pressure gradient is axis symmetry and moves forward with the tunnel excavation;the change of gas pressure before working face and in roadway wall are the same,the gas pressure distribution is parabolic in the gas seepage field, the gas pressure gradient around the roadway is largest,and then it gradually increases to the initial gas pressure. With the increase of exposure time of roadway wall,gas pressure and gas flow in the coal seam around the roadway gradually decreases,and finally tends to be stable.