一种裂隙土的双重入渗模型及对边坡稳定的影响

Double Infiltration Model of Fractured Soil and Its Influence on Slope Stability

在降雨条件下,裂隙的存在为雨水在土中的入渗提供了优势通道,导致雨水在裂隙土坡中的入渗具有不均匀性;裂隙会优先饱和,使得裂隙网络和基质存在水头差,导致基质和裂隙网络存在横向的水流交换.文中将裂隙土表示为由裂隙网络和基质共同组成的双孔隙系统,基于双孔隙模型的Richard渗流方程和伽辽金法,分别求得基质和裂隙网络的压力水头分布,并与Hydrus-1D的计算结果进行了对比分析,验证了该方法的合理性.同时发现,基质和裂隙网络的湿润峰面分布不同,前者陡直,后者平缓.边坡稳定性分析表明,基质宽度越大,雨水入渗影响边坡稳定性的范围越深;当基质宽度变小时,雨水入渗接近均匀入渗,雨水入渗影响稳定性的深度变小,但是饱和度的增加使得浅部土体的抗剪强度降低更大.

Under rainfall condition,the existence of fractures provides advantage for rainfall infiltration which may lead to the uneven distribution of rainwater,and the fractures are preferentially saturated,thus a head difference forms between the fracture network and the matrix and,furthermore,a water flow exchange occurs.In this paper,by representing the fractured soil as a dual-porosity system consisting of fractured network and matrix,the pressure head distribution of the matrix and the fracture network are obtained based on the Richard seepage equation of double-pore model and the Galerkin method,and the results are compared with those of Hydrus- 1D,with the rationality of the method being verified.It is shown that(1)the wet peak surface distribution of the matrix is different from that of the fracture network,the former is steep while the latter is gentle;(2)the wider the matrix,the greater the effect of rainwater infiltration on the slope stability;and(3)when the matrix width becomes smaller,the rainwater infiltration is more and more uniform,and the depth of slope stability affected by rainwater infiltration becomes smaller,while the increase in saturation makes the shear strength of shallow soils decrease more.