# Fragility Assessment of Traffic Embarkments Exposed to Earthquake-Induced Liquefaction
## 1 Introduction  
Natural disasters threaten human lives and possessions practically every day across the globe. According to [PERSON] and [PERSON] [1], most deaths (estimated at more than 800,000) from natural disasters in the last two decades were caused by earthquake events. In addition to the even greater socioeconomic losses due to flooding and extreme weather, losses caused by earthquakes in the last 20 years have exceeded more than US$ 530 billion. All of these losses resulted from either direct ground shaking or the various side effects of an earthquake event, such as a decrease in the shear strength of soil due to the occurrence of soil liquefaction in the ground, which can lead to the failure of infrastructure. Although it is difficult to distinguish the percentage of losses caused by liquefaction alone due to the diverse typology of buildings/engineering infrastructure and other features of the affected area, [PERSON] et al. [2] mentioned that in case of the Costa Rica (1991) earthquake event, approximately 30% of the highway system of the affected area was damaged by liquefaction. In the event of an earthquake, as well as in daily life, the flow capability of different lifelines is of vital importance. For example, the traffic network represents connections between living and work places, as well as between affected areas and assistant institutions in cases of natural disaster. The transportation infrastructure includes road and railway embankments (traffic embankments),built for crossing diverse terrain or due to the needs of split-level junctions. When such engineering structures are located in seismically active areas and underlain by loose, sandy deposits, saturated with groundwater, severe damage can be caused by earthquake shaking and soil liquefaction. Recent earthquakes around the world have indicated the vulnerability of transportation infrastructure to earthquake-induced liquefaction deformations [3; 4; 5; 6]. [PERSON] et al. [7] summarized the damage records of certain strong, historical earthquakes between 1989 and 2003 to traffic infrastructure and other structures due to soil liquefaction and ground shaking. In addition, [PERSON] et al. [8] reviewed the fragility assessment of the transport infrastructure subjected to multiple hazards. In order to decrease the socioeconomic losses related to earthquake events and increase the resilience of society to these, the serviceability of traffic systems needs to be ensured as quickly as possible. With the intention of increasing our knowledge of the soil liquefaction phenomenon and its interaction with traffic embankments (particularly road and railway embankments), an extensive parametric study was conducted in this study. A vulnerability analysis of traffic embankments was performed, using various model geometries and material properties of the liquefiable layer. The result of the vulnerability analysis was a set of fragility curves, which can be used as an engineering tool to represent the probability of exceeding a certain damage state in relation to a selected intensity measure (IM) level. Since soil structure interaction is very complex in the case of soil liquefaction, different failure mechanisms of an embankment can occur, such as slipping of the slope surface, piping failure, crest settlements, lateral spreading, etc. [9; 10; 11]. Consequently, various engineering demand parameters (EDPs) have been used for the derivation of fragility curves. For example, [PERSON] et al. [12] derived fragility curves based on damage datasets from the expressway embankments after a series of earthquakes in Japan. [PERSON] et al. [13] used a factor of safety, while crest settlements are still widely used among other researchers as EDP [14; 15; 16], due to the simplicity of comparing these with field measurements.