Shear Slide Analysis of Sloping Seabed Caused by Waves Using Random Finite Element Method

Waves can cause excess stress and pore water pressure in soils within a sloping seabed, leading to submarine landslides. Notable instances include the Gulf of Mexico in 1969 and the Fraser River Delta in 1985. The dynamic nature of wave loading and the variability of soil properties complicate the stability analysis of seabed slopes. In addition, limited probabilistic studies have been conducted on the instability of submarine slopes in comparison to subaerial slopes. Thus, the analysis of shear slide of seabed slopes composed of highly variable soils is essential. This study aims to investigate the wave-driven slide of isotropic and heterogenous sloping seabed considering uncertainties in shear strength of sediments using Random Finite Element Method (RFEM) coupled with Monte Carlo Simulations (MCS). Hydrodynamic pressure from linear wave theory was imposed on the seabed surface to simulate wave-induced loading. Shear slide analysis models, developed using COMSOL Multiphysics, considered elastic-perfectly plastic soils with a Mohr-Coulomb failure criterion. Spatially variable random fields for soil properties were generated with MATLAB R2022b and incorporated into the COMSOL model. Unlike deterministic analyses, the probabilistic framework developed in this study addressed random spatial variability in soil undrained shear strength (Su), providing failure probabilities across various Su distributions within the seabed depth. The effect of wave climate and statistical parameters (coefficient of variation, normalized spatial correlation length, etc.) on slope failure characteristics were investigated, and the results were discussed.