DEM-DFM Modeling Suffusion of Granular Soils under Triaxial Compression

Suffusion of soils is one of the common hazards in geotechnical and ocean engineering. The influence of the stress condition of soils on suffusion, however, remains unexplored in previous studies. In this study, systematical numerical simulations are performed to investigate the suffusion of soils subjected to triaxial compression using the coupled discrete-element method (DEM) and the dynamic fluid mesh (DFM) approach. By imposing a downward fluid flow, the suffusion in seven gap-graded soil samples with a wide range of fines contents was generated. Conventional triaxial (without suffusion) and suffusion (without triaxial compression) tests were also conducted as comparisons. By taking full advantage of the dynamic mesh technique, this coupled method was able to capture not only the deformation of the soil sample but also the evolutions of pores and microstructures. Simulation results indicate that both the eroded mass and the fluid velocity are significantly increased under the condition of triaxial compression, which can be attributed to the deformation of the pores, the downward movement of the loading wall, and the increased hydraulic gradient during the suffusion. In addition, sensitivity analysis indicates that the percentage of eroded mass increases with the increase of hydraulic head, loading rate, and fines content.