Study on landslide-induced wave disasters using a 3D coupled SPH-DEM method

Landslide-induced waves are a complex fluid–solid coupling phenomenon. A code for coupled fluid–solid simulation was developed on the basis of a coupled SPH-DEM algorithm, enabling the simulation of the whole process of disaster chains covering “Failure → Motion → Wave induction → Wave propagation→Wave-dam interaction” of landslides. The process of wave disasters induced by the landslides down the reservoir near a dam was studied using this method. The fine 3D model depicting the geological structure of landslides as well as their instability mode was built from field survey. Parameters on the contact mechanical characteristics of DEM particles composing landslides were inverted from experiments. Characteristics on the formation and propagation of landslide-induced waves were derived from numerical simulation based on the SPH-DEM coupling method. These characteristics, such as the height of the waves, their impact force on dams, overtopping flow and velocity, and other quantitative information, provide references to reasonably evaluate their disastrous effect. When landslide materials enter the water and generate waves, the surface water stream moves a certain distance and a strong circular current is formed underwater near the entry point. As the stream propagates, its energy declines. On meeting a barrier, it runs up under inertia and becomes breaking waves, thereby generating a huge impact force. The dynamic force of the waves on the dam is the highest when the first wave arrives. In addition, the dynamic force of the waves mainly acts on the upper parts of the dam.