Based on doublelayer embankment foundation

the piping outlet particles’ transgression process is simulated using particle discrete element theory. A stratum model around piping outlet is set up by PFC2D(Particle Flow Code in Two Dimension) software

parameters are confirmed with small scale simulate test

linear contact model and parallelbond model are adopted to simulate the contact relationship of clay and sandy soil respectively. Via soilwater coupling

the whole process of piping evolution is presented. Programs based on FISH language are compiled to acquire the loss mass

porosity factor and velocity of flow. Analysis to the results shows that: the simulation phenomena correspond with the macro phenomena of real piping process. As to mesomechanical results

piping particles run out along a zone which has the maximum velocity of flow

the values scatter of velocity follows the tendency of average to local concentration

the separated tiny channels’ occurrence

caused higher velocity and particles around the zone run out rapidly

thus result in the piping zones formation. These results provide practical warranty for the farther research using PFC2D on seepage failure

and thus provide a new approach to analyze piping problem at mesomechanical scale.