循环荷载下含层理页岩渗透特性试验研究

深入理解含层理以及含宏观裂缝页岩在循环荷载扰动下渗透率的演化规律，对于页岩气隧道安全施工而言意义重大。利用GCTS岩石力学测试系统对含轴向层理及轴向宏观裂缝页岩试件在循环轴向应力和循环围压下渗透率的演化规律开展相关试验研究。结果表明：含轴向层理页岩试件渗透率随轴向应力的加载和卸载基本不发生明显改变，而随围压增加以负指数的形式下降，随围压的减小以指数的形式增加；含宏观裂缝页岩试件的渗透率随轴向应力的加、卸载近似以线性形式降低和增加，而随围压的增大以负指数形式下降，随围压的减小以指数形式增加；含轴向裂缝页岩试件的渗透率相较含轴向层理页岩试件而言有大幅提升，其二者比值约为9倍左右；页岩试件对围压的敏感性约为轴向应力的26倍；试件渗透率几乎不随轴向应力循环次数发生明显改变，而随围压循环次数的增加呈负指数式下降，且其降幅主要集中在第1循环阶段内。研究成果可对页岩气隧道的安全施工提供一定的理论支撑。

Experimental study on the permeability characteristics of laminatedshale under cyclic loading

It is of great significance for the safe construction of shale gas tunnels to deeply understand the evolution law of permeability of laminated shale with macro fractures under cyclic disturbance. The permeability evolution of shale specimens containing axial beddings and axial macro fractures under cyclic axial stress and cyclic confining pressure was experimentally studied using the GCTS rock mechanics testing system. The results show that the permeability of shale specimens containing axial beddings did not change significantly during the loading and unloading of axial stress, but it decreased in a negatively exponential form with the increasing confining pressure and increased exponentially with the decreasing confining pressure. The permeability of shale samples containing macroscopic fractures decreased linearly with the increasing axial stress and increased linearly with the decreasing axial stress, while it decreased in a negatively exponential form with increasing confining pressure and increased exponentially with the increasing confining pressure. The permeability of shale specimens containing axial fractures is significantly higher than that of shale specimens with axial beddings, about 9 times the later one. The sensitivity of shale specimens to confining pressure is about 26 times that to axial stress. The permeability of the specimen almost keeps constant regardless of the number of axial stress loadings and unloadings, but decreases in a negatively exponential form with the increasing confining pressure cycles, and the major reduction occurs in the first cycle. The findings can somewhat provide theoretical support for the safe construction of shale gas tunnels.