In order to show the mechanism of piping development considering development of weak zone

three models are built by means of flume model tests and PFC3D software to study the influence of the extended pore channels on particle migration process. The dynamic process of piping caused by the transportation of fine particles in the soil is studied by sand launder model test of piping and numerical simulation of PFC. Based on the results of the numerical simulation

the rules of the sample’s meso-movement and the liquid’s movement are studied and are compared with the results of sand launder model test. The simulation results agree well with the model test results. The result indicates that the larger the size of weak region

the greater the pressure change

the more loss of particles

the shorter the time to failure is. The result indicates that the critical hydraulic gradient derived by numerical simulation is nearly equal to that derived by sand launder model test and theoretical analysis. Therefore

researching the piping by PFC is reasonable

there are great practical significance and broad application prospects for the study of piping development considering development of weak zone. The results are valuable to further probing into the piping mechanism in sandy soils.