A Numerical Model of Internal Erosion for Multiphase Geomaterials

Internal erosion is the detachment of fine soil particles due to seepage flow, with ensuing increasing porosity, and transport of these particles out of the soil mass. In the present study, firstly we have formulated the constitutive equations of the internal erosion, that is, the erosion criteria and the rate equation of the mass transfer. The driving force for erosion is assumed to be given by the interaction term, i.e. relative velocity between two phases in the equation of motions for the two-phase mixture. Then, field equations to simulate hydro-mechanical behavior due to the internal erosion were derived in the framework of multiphase mixture theory. In addition, laboratory erosion tests using gap-graded sandy soil are simulated by the proposed model and the validity are discussed with respect to the rate of eroded soil mass and the particle size distribution after the erosion test.