Fragility Assessment of Traffic Embankments Exposed to Earthquake-Induced Liquefaction

In this study, a vulnerability analysis of road and railway embankments to earthquake-induced liquefaction deformations was carried out. The result of the vulnerability analysis was a set of fragility curves that were obtained for several embankment and soil-profile geometries, as well as for the material properties of the liquefiable layer. The fragility curves were based on the numerical calculations obtained from FLAC 2D software in conjunction with the PM4Sand material model used for simulating the behavior of liquefaction-susceptible soils during dynamic shaking. The fragility analysis was performed using an incremental dynamic analysis approach considering a set of 30 ground motions and at least eight intensity levels. Permanent vertical displacement of the middle top point of the embankment was selected as the damage parameter, while the intensity measure was expressed in terms of peak ground acceleration at bedrock. Fragility curves were derived for three damage states, including minor, moderate and extensive damage, based on threshold values proposed in the literature. The influence of a single model variable was examined through comparison of the fragility curves.