Seismic fragility evaluation of embankments on liquefiable soils and remedial countermeasures

Abstract

This paper focuses on the evaluation of seismic fragility curves for embankments on liquefiable soils with the aim of improving the reliability of the risk assessment of transport infrastructure systems. Nonlinear dynamic analyses of embankments on liquefiable soils are carried out using the finite difference program FLAC2D with the PM4sand model. Validations of numerical modelling are performed in comparison to the dynamic centrifuge model tests reported in prior investigations. For the establishment of seismic fragility curves, ten input motions are selected and scaled to evaluate the embankment response under increasing shaking intensity levels. The seismic risk of embankments on liquefiable soil is evaluated through fragility curves with the damage states (DSs) described in terms of embankment settlement. The criteria, including correlation, efficiency, practicality, and proficiency, are assessed based on the relationship between the intensity measures (IMs) and the engineering demand parameters (EDPs) for the studied embankments. The embankment responses are compared with the benchmark scenario results to distinguish the relative contribution of the considered liquefaction mitigation strategies (i.e., soil densification, gravel berm, and sheet–pile enclosure). The seismic fragility curve serves as an efficient seismic risk analysis in the selection of liquefaction remedial measures in engineering design.