煤岩全应力应变过程体应变对渗透率的影响

Effect of Volumetric Strain on Permeability of Coal in Complete Stress-strain Process

利用自制WSD-800电液伺服试验装置,将取自南桐东林煤矿6#煤层的煤加工成成型煤样作为研究对象,分别通入He、N2、CH4、CO2气体研究了其全应力-应变过程中的变形特性、有效应力、体应变与渗透率关系。结果表明:(1)型煤样在整个全应力-应变过程中,渗透率与体应变变化关系密切。渗透率先随体应变的增加而降低,到达应变屈服点时渗透率最低,然后随体应变减少而增大。(2)通入的气体不同时,型煤样在全应力-应变过程中体应变随轴向应变变化的变化梯度不同;其梯度的变化与变形的泊松比有关。(3)不同气体条件下的型煤样的渗透率与体应变呈负指数关系。研究成果可为研究煤矿地下开采煤岩体的变形和高效抽采瓦斯提供参考。

Using the self-developed electro-hydraulic servo-controlled experimental equipment,based on the briquette specimens of coal seam 6 of Donglin mine of Nantong Coal Industry Co.,Ltd.,research is carried out on the relationship of permeability with deformation characteristics,effective stress,volumetric strain in complete stress-strain process. The experimental results are shown as follows：（ 1） The permeability is closely related with the volumetric strain of coal briquettes in complete stress-strain process. First,the permeability decreases with the increase in volumetric strain,and reaches the minimum value at the peak point. Then,it increases with the decrease in volumetric strain.（ 2） The gradient values of the volumetric strain change with the axial strain in case of introducing different gases are different in complete stress-strain processes. In different gas conditions,the change of gradient value is related to the Poisson＇s ratio.（ 3） The relationship between permeability and volumetric strain obeys negative exponential distribution. The research results provide a reference for research on underground coal mining and effective development of coalbed methane.