A large amount of loose accumulation materials is deposited on the surface of mountain areas in Southwest China,and the composition is mainly pebble sediment of wide size distributions.Under the action of earthquake,a large number of loose debris can enter the mountainous river in the form of landslide and debris flows,and subsequently change the sediment supply conditions.To study the effect of seismic action on the movement process and deformation characteristics of loose materials,three dimensional particles discrete element method is applied to simulate the movement and deformation of the loose materials on a slope under different seismic loads,and the influence of seismic wave frequency and amplitude on the movement process of loose materials is analyzed and discussed.The simulation results show that the movement of loose materials on a slope can be divided into three stages:starting acceleration,high-speed sliding and decelerating accumulation,and the smaller the particle size is,the slower the particle velocity is.After the particles enter the river,the large particles are accumulated in the front and the surface,and the small particles are found in the middle and low areas.Besides,the effect of the seismic load can greatly reduce the number of contact,resulting in the reduction of collision between particles and the loss of energy of the particles,which leads to a significant increase in the speed and the distance of the loose materials.With the decrease of the frequency of seismic waves and the increase of amplitude,the increase rate of the moving velocity and the moving distance of the particles is enhanced,which will cause the originally stable loose sediment to enter the river,thus increasing the mass of sediment in the mountainous rivers and the damage level of the flash flood disasters.It can be seen that the earthquake has an important influence on the sediment supply conditions of the mountain rivers,which provides a theoretical basis for further research on the disasters after earthquake.
