Survival analysis of a liquefiable embankment subjected to sequential earthquakes

Abstract

In practice, the performance of the structure is studied based on a seismic scenario composed of independent single earthquakes. But in real life, the structure is subjected to multiple earthquakes during its typical design working life, which will produce an evolution of damage with time.The main purpose of this paper is to quantify the liquefaction-induced damage of an embankment due to sequential earthquakes during a defined working life. Moreover, a non-parametric survival analysis is used to estimate the time (in years) until a defined damage level is reached during a specific time interval. For this purpose, a site was chosen where its seismicity and its Probabilistic Seismic Hazard Analysis (PSHA) were identified. First, a site-specific seismic analysis was assessed, that consists in finding the relation between the Intensity Measures (IM) and the Engineering Demand Parameter (EDP). Second, in order to estimate the lifetime distribution as well as the Mean Time To Failure (MTTF) of the embankment, survival functions were drawn. The used time histories were stochastically generated from synthetic ground motion models. In this study, an elastoplastic multi-mechanism soil behavior model was used.According to the obtained results, after the sequential loading, the cumulative damage is either progressive with or without extensive damages or sudden with drastic damages. Moreover, based on the chosen ground motion model, the embankment reaches a moderate damage level before its defined working life. In addition, a numerical parametric analysis is performed in order to quantify the impact of considering (or not) the loading history and the recovery time between each ground motion on the obtained MTTF of the embankment. This study pointed out on the importance of the history of loading since it affects the overall performance of the embankment. Finally, two synthetic ground motion models were assessed in order to generalize, to a certain extent, this work.