Abstract:Submarine landslides,a natural hazard,not only destroy subsea infrastructure but also trigger life-threatening tsunamis.Because of its destructive potential,many scholars are studying the failure mechanism of seabed slopes.There are many factors that induce submarine landslides,e.g.,earthquakes,volcanic eruptions,gas hydrate dissociation, and so on.However,the instability of the seafloor in shallow waters may be induced by waves.This study treats the stability of a submarine slope as a plane strain problem and adopts an elasto-plastic constitutive model obeying the Mohr-Coulomb yield criterion.To analyze seafloor stability under wave loading,a large-scale elasto-plastic finite element program called ABAQUS combined with a strength reduction method is adopted.Based on linear wave theory,wave-induced pressure is implemented by developing a loading module in this program.Pressures are applied on the slope surface as pseudo-static loads at a particular time during the wave period. In addition,a typical example is presented,and a factor of safety (FS) and corresponding critical sliding surface (CSS) for the submarine slope under wave loading are obtained using the improved finite element program.A previously programmed analytical code based on an upper-bound approach of limit analysis is also employed to validate the numerical solutions.Based on this,a series of comparative analyses is performed.The effect of wave parameters such as wave length,wave height,and water depth on slope stability and the positions of the CSS are discussed by comparison with the results from the FEM and upper-bound approach.Some preliminary understanding of the instability mechanism of submarine slopes subjected to wave loading is achieved.The results show that the finite element result is close to the limit analysis result.The factor of safety oscillates with time under static water conditions and decreases gradually with increasing wave length and wave height.In addition,the FS of the submarine slope approach the hydrostatic FS as the water depth increases.This means that when the depth of water reaches a certain value,waves have no effect on the submarine slope.By analyzing the impact of the wave parameters on the CSS,increasing water depth is found to have no influence on the position of sliding surface,but the potential sliding surface position at different times changed significantly.
