Investigating the Effect of Dilatancy Angle and Cohesion on Particle Motion Characteristics Using the SPH Method

The instability process of the slope is governed by cohesion and dilatancy angle. The FEM and limit equilibrium method fail to accurately replicate the impact of cohesion and dilatancy angle on the dynamic instability of the slope. To address this limitation, this study employed a meshfree particle method known as smoothed particle hydrodynamics (SPH). Based on the Drucker–Prager yield criterion and elastoplastic constitutive model, the slope stability program was written in Fortran 90. This computational framework unveils the consequences of increasing the dilatancy angle on particle motion parameters, including velocity, displacement, time, and slope morphology. Furthermore, a comparative analysis was conducted to discern the variations in the sliding surface during slope plastic failure under conditions of zero and nonzero cohesion. This analysis serves to investigate the influence mechanisms of cohesion and dilatancy angle on slope stability. The research findings indicate the following key observations. First, the velocity, displacement, horizontal distance, and plastic strain of particle motion significantly increase as the dilatancy angle increases from 0° to 0.75φ (φ is the friction angle). The total duration of particle movement also increases correspondingly. When particles cease motion, the final morphology characterized by height and accumulation area increases as the dilatancy angle augments. Second, when the dilatancy angle is larger than 0.50 times the friction angle, the further increase in dilatancy angle has no significant effect on the particle motion. Third, when cohesion is zero, the slope fails to develop a shear band extending from the toe to the crest, and the sliding surface primarily adopts a linear form. When cohesion is present, the slope demonstrates an opposing pattern, and the sliding surface is mainly curved.