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为描述采动煤岩渗透率演化过程,引入强度退化指数,基于Hoek-Brown强度准则,建立了考虑围压影响的煤岩应变软化力学本构模型。给出了体积应变和渗透率的关系方程,结合应变软化模型建立了采动煤岩渗透率演化模型,并在FLAC下予以实现。通过数值模拟研究了不同围压下圆柱岩样的峰后应变软化力学行为和某煤矿工作面开采过程中煤岩的渗透率演化过程,结果表明:(1)该模型能较好地反映围压对煤岩峰后应变软化行为的影响;(2)随着工作面推进,越来越多的煤岩单元破坏,渗透率也不断增长,逐渐成为瓦斯等流体运移的主要通道。(3)模型能再现采动煤岩渗透率演化的动态过程,从而为煤与瓦斯共采、煤层瓦斯抽放和瓦斯灾害防治提供指导。
In order to describe the evolution process of coal and rock permeability, the intensity degeneration index was introduced and based on the Hoek-Brown strength criterion, a constitutive model of coal rock strain softening constitutive model was established considering confining pressure. The relationship equation between volume strain and permeability is given. The evolution model of coal and rock permeability is established with strain softening model and implemented under FLAC. The post-peak strain softening mechanical behaviors of the cylindrical rock samples under different confining pressures and the evolution of permeability of coal and rock during the mining of a coal face are studied by numerical simulation. The results show that: (1) The model can better reflect the confining pressure (2) With the advancement of working face, more and more coal and rock units are destroyed and permeability is also continuously increasing, which gradually becomes the main channel of fluid migration such as gas and so on. (3) The model can reproduce the dynamic process of coal-rock permeability evolution and provide guidance for coal and gas co-mining, coal seam gas drainage and gas disaster prevention and control.