A new approach for evaluating the seismic stability of viscoelastic soil slopes considering geometric boundary condition and vertical inertial force

Simplifying the inertia force is the key to evaluating the seismic stability of the slope. In this paper, a simplified method for calculating seismic forces in slopes, termed MPDM S , is proposed based on the modified pseudo-dynamic method (MPDM) and the actual stress boundary conditions of slopes. By integrating MPDM S with the simplified Bishop method, a formula for slope seismic stability is derived. Results show that MPDM S can effectively capture the dynamic response characteristics of slopes. As frequency increases, the average amplification factor of slopes calculated by MPDM S first rises and then declines. Parameter analysis shows that safety factor (F s ) improves with increasing cohesion, internal friction angle, and damping ratio, while it decreases with greater slope angle and wave amplitude. Moreover, as the shear modulus and frequency increase, the F s of the slope initially decreases and then increases. Overall, an increase in unit weight and slope height is generally detrimental to seismic stability. Furthermore, this study analyses the impact of vertical seismic loads on slope stability based on MPDM S . The results indicate that while vertical seismic loads have a significant influence on slope stability, horizontal seismic loads remain the dominant factor. The findings of this study can provide a theoretical foundation for seismic hazard assessment of slopes, earthquake-induced landslide prediction, and earthquake emergency rescue.