Response characteristics of soil slope under mainshock-aftershock sequences-type ground motions: Incremental damage effect, polarity effect, and correlation

Abstract

Aftershocks frequently induce further damage to slopes that have already been compromised by mainshocks. Most of the current research concentrates on the case-based studies of structural response to the mainshock-aftershock sequences (MAS), however, the influence of the MAS parameter characteristics has not been adequately considered. In this study, the peak characteristic, spectrum characteristic, cumulative characteristic and polarity effect of the MAS were considered, the correlation between 21 MAS parameters and slope response were analyzed, and the response characteristics of soil slope under the MAS action were comprehensively and systematically revealed. The results show that: (1) Aftershocks can induce significant incremental damage to slopes, with the extent of this damage being contingent upon the severity of damage caused by the mainshock; (2) Among the MAS parameters, the Cumulative Absolute Velocity (CAV_ma) and Peak Ground Velocity (PGV_ma) are optimal for assessing the response of soil slopes under MAS conditions. Furthermore, the incremental damage caused by aftershocks can be predicted using the displacement increment ratio (δ_D); (3) The polarity of the MAS has an impact on the displacement of the slope, following the pattern: MAS along-slope direction > mainshock along-slope direction and aftershock reverse-slope direction > aftershock along-slope direction and mainshock reverse-slope direction > MAS reverse-slope direction; (4) The MAS polarity also affects the correlation between the MAS parameters and the slope displacement response, especially for the aftershock displacement. The research results aim to provide a foundation for the selection of evaluation factors and the analysis of soil slopes stability under the MAS action.