Mesoscopic numerical simulation for suffusion process of gap-graded sandy soil

To investigate the meso-mechanism of suffusion between gap-graded sandy soil, the discrete element method coupled with computational fluid dynamics was used to simulate the suffusion process of nine groups of graded soils based on Kézdi’s criteria. The changes of the meso-parameters of the internal stable soil and the unstable soil during the erosion process were analyzed, and the influence of the initial flow rate on the erosion process was discussed. The results show that the eroded process of soil can be divided into four stages, i.e., initiation, development, transition and progression. The particle size distribution of soils directly affects the development of erosion. The larger the gap ratio is, the less stable the soil is, and it is easily eroded. When the gap ratio is greater than 4, the initiation stage of soil suffusion is short, the erosion rate in the development stage is large and has a steady growth trend in the progression stage. At the same gap ratio, the mass fraction of fine particles rarely affects the initial stage and development stage of the erosive curve, but the more the fine particles are, the greater the erosion rate is at the continuation stage. The fluid boundary condition is an important external factor. For easily erosive soils, when water flow rates exceed the critical value, the erosion rate still maintains an increasing trend in the progression stage. For the internal stable soil, the flow rate hardly affects the stable tend of the erosion rate in the progression stage. © 2019, Central South University Press. All right reserved.