Simulation and verification of landslide tsunamis using a 3D SPH-DEM coupling method

Abstract

Landslide tsunamis represent a highly complex fluid-solid interaction process and this complexity is one of the challenges in researching landslide disasters. Given the characteristics of landslide tsunamis, a coupled smoothed particle hydrodynamics (SPH)-discrete element method (DEM) code was developed and applied to simulate the process in this study. Based on the laboratory experiment that Fahad (2010) carried out on the tsunami process produced by granular slides, numerical tests with the same conditions as the experiment were performed. Except for a small influence on the infiltration of water into the pores in the slide in the generation area of the tsunami, the ratio of 1/6 of the DEM particle diameter to the scale of the SPH particles is better for simulating landslide tsunamis based on the SPH-DEM coupling method. According to the numerical results of the tsunamis generated by five types of slides with the same geometry and weight, the slide type significantly affects the tsunami characteristics. During the transition from the slope toe to the bottom of the water tank, different slide type exhibit different changes in the slide geometry, resulting in significant differences in energy loss, transfer of kinetic energy from the slide to the water, and the water-entry volume of the slide, which in turn affect the behavior of the tsunami. As a whole, under the same conditions, the speed and amplitude of the initial tsunami generated by a granular slide are lower than those generated by a blocky slide, with a blocky slide composed of four blocks generating the highest tsunami speed and amplitude.