低应力与覆水环境下单裂隙粉砂质泥岩渗流特性

为探究不同外部环境因素影响下浅层粉砂质泥岩边坡裂隙渗流特性，采用自主研发的岩体裂隙渗流试验装置，对含6种不同裂隙面粗糙度（JRC）的粉砂质泥岩裂隙试样进行渗流试验，研究了不同低围压和覆水深度下粉砂质泥岩裂隙渗流特性。结果表明：不同覆水深度及JRC下围压与粉砂质泥岩裂隙渗透系数均呈反相关，两者之间关系可用幂函数表征，且渗透系数的降低过程可分为快速降低（围压为0～30 kPa）和缓慢降低（围压为30～50 kPa）两个阶段，CT扫描结果验证了围压增大使得粉砂质泥岩裂隙开度减小是渗透系数随围压增大而减小的主要原因。随围压的增大或覆水深度的减小，不同JRC粉砂质泥岩裂隙渗透系数的离散程度逐渐减小。当围压增至最大，同时覆水深度最小时，JRC对裂隙渗透系数的影响将会被消除。不同围压下，粉砂质泥岩裂隙渗透系数与覆水深度呈正相关，且两者关系可用指数函数表征。推导出了粉砂质泥岩裂隙渗流非线性Izabsh模型，该模型能较好地反映低应力及低流速下粉砂质泥岩裂隙渗流量与压力梯度之间的非线性变化关系，但随围压的增大，该模型的相关性有一定程度的减小。

Seepage characteristics of single-fracture silty mudstone under low stress and overlying water environment

In order to explore the seepage characteristics of fractured rock mass in the shallow silty mudstone slope under different environmental conditions, a self-developed fractured rock mass seepage apparatus was used to conduct seepage tests on fractured silty mudstone samples with six different fracture surface roughnesses (JRC). The seepage characteristics of fractured silty mudstone under different confining pressures and overlying water depths were studied. The results show that the permeability coefficient of silty mudstone is inversely correlated with the confining pressure under different overlying water depths and JRCs, which can be characterized by a power function. The reduction of permeability coefficient can be divided into two stages: a rapid reduction (0? 30 kPa) and a slow reduction (30?50 kPa). CT scanning results confirm the main reason for the decrease of permeability coefficient is that the increase of confining pressure causes the decrease of fracture aperture of silty mudstone. With the increase of confining pressure or the decrease of overlying water depth, the discreteness of fracture permeability coefficient of different JRC silty mudstone decreases gradually. When the confining pressure increases to the maximum and the overlying water depth is the minimum, the effect of JRC on permeability coefficient would be eliminated. It is also found the permeability coefficients of the samples are positively correlated with the overlying water depth under different confining pressures, which can be characterized by an exponential function. Moreover, the nonlinear Izabsh model of seepage flow in fractured silty mudstone is derived, which can better reflect the nonlinear relationship between seepage flow and pressure gradient under low stress and low velocity. However, the correlation of the model decreases with the increase of confining pressure.