Influence of ground motion duration on the seismic performance of earth slopes based on numerical analysis

Abstract

Assessing the dynamic stability of earth slopes is an important topic in geotechnical engineering field. In this study, the duration effect on the seismic performance of a multi-layer earth slope is quantitatively investigated, using two pairs of ground-motion suites selected matching a scenario-based response spectrum and a design spectrum, respectively. The four ground-motion suites are selected from the NGA-West2 database, with each pair of suites exhibiting a consistent distribution of response spectra yet different distributions of significant duration. Numerical analyses using the selected ground-motion suites as input are then conducted for the earth slope implemented in FLAC. Comparative results indicate that as compared to the shorter-duration suites, using the longer-duration ground-motion suites generally yields similar topographic acceleration-amplifications but an enlarged distribution of permanent slope displacements. Therefore, the influence of ground-motion duration on seismic-wave amplifications is insignificant; such influence on the earthquake-induced slope displacements is, however, significant. Using the selected longer-duration ground-motion suites, the slope (moderate) damage and failure probabilities exceeding specific displacement thresholds are increased by up to 20% and 50%, respectively. Therefore, when assessing the seismic performance of earth slopes in applications, one should pay adequate attention to the ground-motion duration effect, and input motions shall be selected in such a way that the duration characteristics of ground-motion records are properly constrained.