Abstract: The study on migration and deposition of suspended particles in subgrade is important to reveal the generation and disaster-causing mechanism of mud pumping. The effects of dynamic load magnitude, intermittent duration of static load, and repetition number of alternating dynamic loads and static loads on particle migration and deposition have been studied by carrying out the mud pumping test of layered gravel-sandy silt column. According to the hydrodynamic response characteristics of specimens, the driving mechanism of particle migration was analysed. The test results show that the suspended particles migrate upward under hydrodynamic force and settle under gravity during the interval of static load, which results in the fluctuating growth of slurry turbidity in the gravel layer. The particle suspension increment tends to decrease with increasing repetition of alternating dynamic loads and static loads, and these particles gradually clog gravel pores and inhibit mud pumping to a certain extent. Increasing dynamic frequency and dynamic stress can further reduce the internal stability of the sandy silt surface layer. However, compared with increasing dynamic stress, increasing loading frequency is more beneficial to increase the particle migration mass and vertical migration distance.