A fully nonlinear coupled seismic displacement model for earth slope with multiple slip surfaces

For slopes consist of layered soil profiles, the earthquake-induced deformation may occur in various locations and the slope may exhibit a set of plastic slip surfaces. In this paper, a fully nonlinear coupled sliding displacement model is presented to evaluate the seismic performance of slopes considering multiple slip surfaces. Both the nonlinear behavior in the cyclic response of soils and the sliding process at different slip surfaces are described based on a multi-degree-of freedom lumped parameter model. The nonlinear hysteretic soil response is represented by the hyperbolic stress-strain curve and the Masing rules. The yield coefficients obtained from pseudo-static analysis of slopes are used to represent the limit shear strength at each slip surface. The dynamic equations of motion of the system in the cases of various sliding modes at shallow, median and deep slip surfaces are derived, and the sliding displacements at different locations of slopes during the earthquake motion can be computed. The code is validated by degrading the developed model to the conventional seismic site response analysis and seismic sliding analysis models. The sliding displacement at different slip surfaces and the stress-strain results of soil are analyzed to highlight the coupling effects of the plastic shear deformations at different slip surfaces and the cyclic responses of soil. The comparisons of displacement results for different slopes are then performed between the proposed model and the linear soil model and the single sliding analysis model. Finally, an application to the Bainigou slope is presented to evaluate the seismic performance of the slope.