Vibration effects of particle size and volume and their influence on landslide mobility via the discrete element method

Particle shear vibration frictional weakening is a major cause of high-speed and long-distance landslides. To reveal the mechanism of shear vibration frictional weakening during landslide movements, a flume simulation model was established using the discrete element method (DEM), and the effects of volume and particle size on particle vibration, basal stress and particle fluidity were studied. With increasing volume, the Arias intensity and dominant frequency of the basal vibration (stress) increase. However, the particle size is positively correlated with the Arias intensity of the basal vibration and is negatively correlated with the dominant frequency. The evolution trend of the average basal normal stress exhibited three stages: rising, slow decay and rapid decay. Both the average basal normal stress and the basal fluctuating stress are positively correlated with volume. An increase in particle size not only delays the occurrence of the average basal normal stress peak but also promotes an increase in the basal fluctuation stress. The volume and particle size of a particle significantly affect its fluidity. An increase in volume and particle size will lead to a decrease in the effective friction coefficient and apparent viscosity of the particle flow; the velocity profile of the particle flow will exhibit a nonlinear distribution of decreases from top to bottom, and the velocity gradient will also increase with increasing volume and particle size.