Modelling the sequential earthquake-tsunami response of coastal road embankment infrastructure

Abstract

Transport networks in coastal, urban areas are extremely vulnerable to seismic events, with damage likely due to both ground motions and tsunami loading. Most existing models analyse the performance of structures under either earthquakes or tsunamis, as isolated events. This paper presents a numerical approach that captures the sequential earthquake-tsunami effects on transport infrastructure in a coastal area, taking into consideration the combined strains of the two events. Firstly, the dynamic cyclic loading is modelled, applied to the soil-structure system using a finite-difference approximation to determine the differential settlement, lateral displacement and liquefaction potential of the foundation. Next, using a finite-volume method approach, tsunami wave propagation and flooding potential are modelled. Finally, the hydrostatic and hydrodynamic loads corresponding to the wave elevation are applied to the post-earthquake state of the structure to obtain a second state of deformation. The sequential model is applied to an embankment in Manzanillo, Mexico, which is part of a main urban road; the response is analysed using ground motion records of the 1995 Manzanillo earthquake-tsunami event.