CORRELATION ANALYSIS OF SLOPE DISPLACEMENT RESPONSE AND SEISMIC PARAMETERS DUE TO MAIN-AFTERSHOCK SEQUENCES

Slopes are vulnerable during strong earthquakes, and earthquake-induced landslides have caused serious casualties and economic loss. At present, researchers mainly focused on the seismic slope displacements subjected to the mainshocks. However, the influence of aftershocks on slope stability is ignored. To address this issue, 210 recorded main-aftershock sequences are selected in this study, which are subsequently used as input ground motions for the numerical analysis of slopes. Based on the finite difference software FLAC, the slope displacements caused by the main-aftershock sequences are analyzed, and the incremental displacement ratio is used to quantify the influence of the aftershocks on the slope responses. Fifteen ground motion intensity measures (IMs) are further selected, and the correlations of the IMs of mainshocks, of aftershocks, of the main-aftershocks with mainshock-induced displacements, of aftershock-induced incremental displacements, and of the main-aftershock induced total displacements are studied, respectively. The results show that aftershocks can produce significant vertical permanent displacement increments, some of which are even greater than the mainshock-induced displacements. The IMs of the mainshocks exhibit the strongest correlations with the main-aftershock induced slope displacements. Among the ground motion IMs considered, the spectral acceleration at the slope's fundamental period and acceleration spectrum intensity of the mainshocks (Sa(T_s)_M and ASI_M, respectively) exhibit the strongest correlation with the main-aftershock induced displacement. Finally, predictive models for the main-aftershock displacements are proposed based on the two optimal IMs identified, and the performance of the models is satisfactory.