A simplified nonlinear coupled Newmark displacement model with degrading yield acceleration for seismic slope stability analysis

The use of Newmark permanent displacement to preliminarily evaluate the seismic performance of earth slopes has been well accepted in geotechnical community. Essentially, the seismic displacement would cause slope soil shear strength to reduce, thus causing the slope yield acceleration to degrade during the earthquake shaking. This phenomenon is known as degrading effect of yield acceleration, which has not been fully addressed in the literature. In this study, the degrading effect is investigated on the basis of various Newmark's displacement calculation frameworks for infinite slopes. Specifically, the flexible‐deformation‐recoverable soil columns as well as the nonlinear soil dynamic properties including the damping and shear modulus are taken into account to derive the coupled Newmark model. Detailed discussions are made to the possible influence of the degrading effect of yield acceleration in different schemes of Newmark displacement calculation frameworks. The parametric studies show that the seismic displacement calculated by the proposed method reaches peak value at small period ratio, and dramatically drops to zero when the period ratio increases. Furthermore, the possible influence of shear rate on soil shear strength is also discussed.