Numerical simulation of piping-filter prevention in sandy soil by discrete element method

Combining with the small-scale model tests and using Particle Flow Code based on discrete element method, the seepage erosion model established with the coupling of solid and fluid taken into account. The numerical model of base soil-filter system during seepage in sandy soils is simulated under various coefficients between layers. The variations of the path of moving particles, loss fraction of gains, porosity, permeability, contact force, hydraulic gradient of particles, and etc are traced and recorded. The movement Characteristics of particles and the filter prevention mechanism are studied from the viewpoint of meso-mechanics. The results show that the coefficient between layers(D15/d85s) is important to the effectiveness of filter layer. Following the accretion of hydraulic gradient, under the effective coefficient between layers, the self-filter phenomenon exists in the base soil-filter interface when the movable particles of base soils entering into the filter layers. The rationality of the proposed numerical method is validated by comparing the numerical solutions with the relative experimental results. The results are valuable to probe into the piping and filter mechanism in sandy soils further.