Abstract This paper investigates the effect of suffusion on the undrained behavior of an internally unstable soil using the coupled computational fluid dynamics and discrete element method (CFD-DEM). A series of eroded specimens are prepared by exerting an upward flow through the granular assembly under a range of hydraulic gradients and suffusion durations. Both the eroded and non-eroded specimens are then subjected to undrained triaxial compression (or equivalently constant volume tests). The results indicate that the erosion rate and volumetric response of the soil skeleton are closely related to the hydraulic conditions. The eroded specimens exhibit a non-uniform distribution of fine particles, higher coordination numbers, higher global void ratio, and lower equivalent intergranular void ratio. The undrained behavior of the specimen changes from a strain hardening behavior before suffusion to a softening behavior with limited flow deformation after suffusion. The undrained shear strength of eroded specimen is enhanced at small axial strain due to the enhanced connectivity of particles, but can increase or decrease at larger strain levels depending on the degree of erosion. It is also observed that both suffusion and shearing can induce some degree of fabric anisotropy by inspecting the directional distribution of contact unit normals and contact normal forces.

中文翻译：

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CFD-DEM 模拟对内部不稳定土壤不排水行为的扩散效应

摘要 本文使用耦合计算流体动力学和离散元方法 (CFD-DEM) 研究了扩散对内部不稳定土壤不排水行为的影响。通过在一定范围的水力梯度和扩散持续时间下通过颗粒组合施加向上流动来制备一系列侵蚀样品。然后，侵蚀和未侵蚀的试样都经受不排水的三轴压缩（或等效的恒定体积试验）。结果表明，土壤骨架的侵蚀速率和体积响应与水力条件密切相关。侵蚀试样表现出细颗粒分布不均匀、配位数较高、整体空隙率较高和等效晶间空隙率较低。试样的不排水行为从扩散前的应变硬化行为转变为扩散后流动变形有限的软化行为。由于颗粒的连通性增强，侵蚀试样的不排水剪切强度在较小的轴向应变下增强，但在较大的应变水平下可以根据侵蚀程度增加或减少。还观察到，通过检查接触单元法线和接触法向力的方向分布，扩散和剪切都可以引起一定程度的织物各向异性。但可以根据侵蚀程度在较大的应变水平上增加或减少。还观察到，通过检查接触单元法线和接触法向力的方向分布，扩散和剪切都可以引起一定程度的织物各向异性。但可以根据侵蚀程度在较大的应变水平上增加或减少。还观察到，通过检查接触单元法线和接触法向力的方向分布，扩散和剪切都可以引起一定程度的织物各向异性。