Coupled analysis of earthquake-induced permanent deformations at shallow and deep failure planes of slopes

The seismic performance of slopes is commonly evaluated by simplified sliding block analyses. In this paper, an extended sliding block model is developed to compute the earthquake-induced deformations at both shallow and deep failure planes of slopes. The coupled analytical model captures simultaneously the stick-stick, stick-slip and slip-slip behaviors of the lumped mass system of soil profile. The complex interactions between the dynamic response of the soil and the slip episodes at shallow and deep slide planes are revealed. The proposed sliding model is compared to the conventional single base-sliding analyses, and the influence of the presence of shallow failure sliding is emphasized. Then, the dynamic response and permanent displacement of slopes with different locations of the shallow sliding plane and different yield accelerations of shallow and deep sliding planes are examined. The comparisons are also performed for permanent displacements determined from the developed coupled multi-sliding procedure and from the seismic sliding model with multiple rigid blocks. Finally, an example is presented to demonstrate the procedure in the application and the differences of the results from the traditional coupled approach. The coupled model in this study provides a rigorous procedure to combine the shallow and deep failure modes for the assessment of the co-seismic landslide hazard.