淮南矿区典型煤岩体全应力—应变渗透性表征试验

煤岩体是一种多孔介质，地下开挖使岩体的应力状态发生改变，导致岩体的力学性质和渗透性质发生改变，围岩应力状态和渗流场特性是获取储层瓦斯气、评价或计算矿井涌水量、防突水危害等具体工程问题的理论基础和科学依据。通过对淮南矿区煤岩进行三轴压缩全过程渗透性试验，分析了煤岩变形破坏全过程以及不同围压和瓦斯压力下的瓦斯渗透特性。得出煤岩全应力—应变曲线与煤岩瓦斯渗透率—全应力应变曲线之间的对应关系。结果表明:在微型裂隙闭合和弹性变形阶段，煤样渗透率随应力增大而减小，进入屈服阶段后，渗透率达到最小值并在峰值后呈持续增大之势；固定瓦斯压力作用下，煤样应力峰值随着围压的增加而逐渐增大，煤样渗透性与围压关系呈指数函数变化规律，且表现出应变滞后的特点；固定围压作用下，渗透率与瓦斯压力关系呈“V”字型走势，即在扩容阶段煤岩样渗透性达到最佳。

Test on permeability properties of typical coal specimen during complete stress-strain process in Huainan Mining Area

Coal-rock mass is a kind of porous medium.Underground excavation changes the stress state of rock mass，which leads to the change of mechanical properties and permeability properties of rock mass.The stress state and seepage field characteristics of surrounding rock are to obtain reservoir gas，evaluation or the theoretical basis and scientific basis for calculating specific engineering problems such as mine water inflow and water inrush damage.Through the whole process permeability test of coal and rock in Huainan mining area，the gas permeability and failure characteristics of coal and rock under different confining pressure and gas pressure were analyzed.The correspondence between the full stress-strain curve of coal rock and the permeability of coal rock and the full stress strain curve was obtained.The results show that in the stage of micro-fracture closure and elastic deformation，the permeability of coal sample decreases with the increase of stress.After entering the yield stage，the permeability reaches the minimum value and continues to increase after the peak；under the action of fixed gas pressure，the peak value of coal sample stress increases with the increase of confining pressure.The relationship between coal permeability and confining pressure changes exponentially and exhibits strain hysteresis.Under the action of fixed confining pressure，the relationship between permeability and gas pressure，it has a "V" shape，which is the permeability of coal rock samples is optimal during the expansion phase.