A novel failure surface predictive method for low-angle submarine slopes and coupling effects with monopile foundations

Existing FE methods have significant limitations in simulating the stability of low-angle, low-shear-strength submarine slopes with engineering structures such as monopiles. Therefore, the present study aims to develop a novel prediction method for the potential submarine slope failure surface based on the Mohr-Coulomb criterion and the shear strength reduction method, drawing on extensive FEM and LEM simulation results. By comprehensively investigating the shear strength and stress distribution at the base of the slope, a predictive relationship between the critical reduction factor and the critical slope failure angle was established. This was then used to predict and analyse the critical failure angle in 3D homogeneous curved slopes and 3D complex real-world seabed topography. The model results and validations demonstrate the present method is robust and accurate. Furthermore, when a large slope contains multiple secondary slopes, this approach can simultaneously capture several discontinuous potential failure surfaces, addressing the non-convergence issues of FEM in these problems. Finally, the present method is used to investigate the spatial distribution of landslide areas and their impact on the stability of monopiles in offshore wind farms over a 3D topography at Silver Pit near the coast of Lincolnshire and North Norfolk, UK with historical records of submarine landslides.