应力-损伤-渗流耦合模型及在深部煤层瓦斯卸压实践中的应用

根据瓦斯渗流与煤体变形的基本理论,引入煤体变形过程中应力、损伤与透气性演化的耦合作用方程,建立了含瓦斯煤岩破裂过程固气耦合作用模型。应用该模型模拟分析了深部采动影响下瓦斯抽放过程中煤层透气性的演化和抽放孔周围瓦斯压力的变化规律,认清了开采卸压瓦斯瞬态渗流的力学机制。模拟结果表明,采动影响使得处于其上部67m的煤层卸压,透气系数增大了2000多倍,卸压范围70m左右,同现场实际观测结果比较吻合。这对于进一步深入理解开采过程远程卸压瓦斯渗透性的演化、瓦斯抽放渗流的机制具有重要的理论和实践意义。

COUPLING MODEL OF STRESS-DAMAGE-FLOW AND ITS APPLICATION TO THE INVESTIGATION OF INSTANTANEOUS SEEPAGE MECHANISM FOR GAS DURING UNLOADING IN COAL SEAM WITH DEPTH

On the basis of basic theories of gas flow and coal deformation,the coupled gas-rock model for investigating the failure process of coal-rock is established by introducing the related equations governing the evolution of stress,damage and gas permeability along with the deformation of coal and rock. Implemented with rock failure and process analysis code (RFPA),this model can be used to capture the evolution of gas permeability in coal seam at great depth and the distribution of gas pressure around the drilling hole,and explore the instantaneous seepage mechanism of gas flow. From the simulated results,it can be found that the coal seam, located around 67 m above the excavated seam,is under unloading state and its gas permeability dramatically increases about 2 000 times as that excavated in underlying coal seam,and the size of the unloading region is around 70 m in diameter. The simulated results are in good accordance with the in-situ results. Therefore,it is safe to say that this numerical tool is of significance in both theory and practice to investigate the evolved mechanisms of gas permeability and gas drainage.