A convex hull-constrained SPH-DEM model for simulating soil-rock mixture landslide dynamics

• A convex hull-constrained SPH-DEM model is proposed for simulating the soil-rock mixture landslide dynamics. • The constraint detection process is implemented to avoid rock overlap and penetration. • A soil-rock mixture flow impact experiment is simulated to validate the proposed model. • The 2016 Anhua landslide event in China serves as a case study to examine its application performance. Analyzing soil-rock mixture landslide dynamics using the coupled SPH-DEM method holds significant potential. However, limited rock distribution data and complex landslide domains make coupled SPH-DEM models heavily reliant on manual or random rock placement, leading to inefficiency and non-physical issues like overlap and penetration, significantly compromising simulation reliability. In this paper, a novel convex hull-constrained SPH-DEM model (CHC-SPH-DEM) is proposed, incorporating an advanced rock group distribution algorithm to effectively position highly irregular DEM rocks. Furthermore, a constraint detection and position update mechanism is introduced to prevent rock penetration and overlap. A soil-rock mixture flow impact experiment is simulated to validate the proposed model, which demonstrates higher simulation accuracy compared to traditional manual placement methods. The 2016 Anhua landslide event in China is selected as the case study to further explore its application performance. Results indicate that the proposed model not only performs well in analyzing large-scale soil-rock mixture landslide dynamic behaviors, such as flow velocity, flow depth, and kinetic energy evolution, but also effectively captures rock-phase behavior, provides predictive insights into potential structural damage, and reveals that structures located closer to the landslide area may face greater hazards. Several discussions on the model conclude the paper.