Effect of Excitation-Applied Manners on Permanent Displacements of Planar Slopes Using Dynamic Sliding Blocks Analysis

Abstract

The sliding block model is widely used to evaluate the stability of slopes under earthquakes. In this model, the horizontal ground motion is usually applied to the parallel to the slope, whereas the vertical ground motion is commonly ignored. This study investigated the effects of different excitation-applied methods (EAMs) on slope permanent displacements (PDs) using a general sliding block model. For this purpose, three types of ground motion records selected from the NGA-West2 database were applied with six different EAMs to a series of gentle/steep slope sliding systems whose critical accelerations ac ranges from 0.01 to 0.40g. Comparison of the PDs obtained from the two-dimensional (2D) EAM and the other five systems reveal the following: (1) the common practice of applying a one-dimensional (1D) input motion excessively underestimates the PDs of sliding systems, particularly for those with large slope angles and large critical accelerations; and (2) the effects of the vertical component on the arithmetic mean of PDs are ignorable although the impact can reach several times for some cases in which the slopes are located in near-fault areas and affected by pulse-like ground motions. Besides, it is demonstrated in this study that applying the horizontal and vertical base motions simultaneously to the slope can be the most suitable excitation-applied manner for seismic slope stability analysis in the near-fault zone.