Seismic fragility analysis of railway embankment structures considering shallow bedrock ground conditions

초록

Railway embankment structures are a key component of linear infrastructure and may affect the operation of the railway network during earthquakes due to structural damage and safety-related operational restrictions. Accordingly, seismic fragility analysis is essential for evaluating the seismic response and damage potential of railway embankment structures. In this study, the seismic fragility of railway embankment structures was evaluated under ground conditions characterized by relatively shallow bedrock, with Korea considered as a representative example of such conditions. To account for these characteristics, site classification criteria (S1-S5) defined in the Korean Design Standard (KDS 17 10 00) were applied. Bedrock depth, shear wave velocity of the underlying soil layer, and embankment height were considered as key parameters, and seismic fragility functions were derived using permanent vertical displacement obtained from nonlinear dynamic time-history analyses. The fragility analysis results indicate that seismic fragility increases with increasing bedrock depth and decreasing shear wave velocity of the soil layer. In addition, the influence of embankment height varies depending on ground conditions, with ground amplification effects exerting a stronger influence on the seismic response under soft ground conditions, whereas inertial effects associated with increased embankment mass become more influential under relatively stiff ground conditions. Overall, this study provides fundamental data for the seismic performance evaluation and seismic design of railway embankment structures located on ground characterized by shallow bedrock.

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