Landslide mechanisms under rapid sedimentation of marine clay in shelf-slope break

A numerical method is developed for analyzing the landslide mechanism of layered sediment slopes at the shelf-slope break based on a coupled hydro-mechanical model. The parameters of the numerical model are determined through experimental measurements of seabed sediments. The numerical method is used to simulate the evolution of submarine landslides in the shelf-slope break, and to investigate the variation of excess pore pressure, shear strain and void ratio at the landslide location under rapid sedimentation. It was founded that with the sediment loads, the excess pore pressure in the submarine sediment increases continuously, and the value of maximum excess pore pressure in the critical state reaches 302.4 kPa, creating favorable conditions for submarine landslides. The shear strain at the submarine landslide stratum increases rapidly along the depth to the critical point and then decreases rapidly, and the maximum strain manifests at the potential sliding surface of the submarine slope. The rapid sedimentation significantly increased the excess pore pressure and shear strain of the soil in the landslide area, resulting in submarine landslide. The mechanism presented in this paper is widely applicable and provides a basis for the stability assessment of submarine slopes.