Numerical simulation study of impact effects in soil-rock mixture landslides using moving particle semi-implicit method-rigid body coupling method

To investigate the influence of rock block content and spatial distribution on the movement characteristics and impact effects of soil−rock mixtures in slopes. A moving particle semi-implicit (MPS)−rigid body coupling method based on the Bingham fluid model and the Navier−Stokes equations was proposed, in which MPS particles were aggregated into cluster-shaped rigid bodies to simulate rock blocks. A series of numerical simulations were carried out to systematically analyze the effects of rock content (0%−40%) and block distribution (upper, middle, and lower parts of the slope) on landslide motion and impact forces on building structures. The results show that the impact force increases quadratically with rock content, with a critical threshold of 20% where the influence becomes pronounced. The spatial distribution of rock blocks significantly affects the impact behavior: blocks in the upper part act as “drivers” and produce the maximum impact force, whereas those in the lower part act as “brakes” due to frictional resistance. This study provides a numerical basis for risk assessment and protective design of soil−rock mixture landslide hazards.