A Fully-Resolved Simulation Study of Seabed Liquefaction and Dynamic Response Using a Coupled LBM-IBM-DEM Approach

Wave-induced seabed liquefaction is a common factor leading to submarine instability, primarily occurring in silty seabeds. Under wave action, the pore water pressure within the seabed continuously increases. When the pore water pressure approaches or exceeds the total stress of the soil, the effective stress of the soil tends toward zero, resulting in liquefaction. Currently, most models of seabed dynamic response are based on macroscopic constitutive equations derived from Biot’s consolidation theory, making it difficult to accurately reveal the mesoscale mechanisms of seabed behavior under wave loading. This study employs a coupled numerical approach integrating the Lattice Boltzmann Method (LBM), the Immersed Boundary Method (IBM), and the Discrete Element Method (DEM) to systematically investigate the dynamic response and liquefaction process of a seabed under wave action. In this model, DEM is used to describe the motion and interactions of seabed sediment particles, LBM is applied to simulate fluid flow behavior, and IBM handles the coupling effects between particles and the fluid. Additionally, to improve computational efficiency, local grid refinement is applied near the seabed region, enhancing overall calculation performance. Using this coupled model, the periodic variations of wave-induced pore water pressure and effective stress in the seabed are studied, and the simulation results are validated against experimental data. The results show good agreement between simulations and experiments, accurately reflecting the dynamic response characteristics of the seabed under wave action. The model not only reveals the interaction mechanisms between soil particles and pore fluid from a microscopic perspective but can also be further extended to study the coupled effects of liquefaction and scour on near-bed sediment transport, offering significant theoretical insights and practical engineering value.