Earthquake response and post-earthquake stability assessment of submarine clay slopes

Earthquakes are the most frequent trigger for submarine landslides; thus, seismic instability evaluation of submarine slopes has received considerable attention. Previous studies have usually regarded earthquake response and post-earthquake stability assessment of submarine slopes as two separate procedures. However, earthquake response processes significantly affect the strength degradation of the soil. Notably, relevant research on this subject is rare. Herein, a general approach is proposed to predict the earthquake response and to assess the post-earthquake stability of submarine slopes. First, an earthquake response computational method is developed for an actual submarine slope with curvilinear geometry, which utilizes the SIMPLE DSS model. The calculated results of the earthquake response are used to determine the seismic strength degradation factor. Subsequently, the position and length of the initial shear band can be determined. A modified shear band propagation (SBP) criterion is used to assess the post-earthquake slope stability after addressing the uneven strength reduction of the soil in a weak layer after an earthquake, and the slope geometry effect on stability is discussed. Finally, the proposed approach was applied in a stability risk assessment of an actual submarine slope. For geologists and engineers to evaluate the stability of submarine slopes experiencing earthquakes, this method is practical and efficient.