ABSTRACT
In this research, typical deep circular tunnel sections in soft soils of Shanghai city are used as case studies to reveal the time-dependent fragility functions for deep circular tunnels in soft soils. The seismic performance of the tunnel lining is obtained based on a series of nonlinear dynamic analyses of the soil-tunnel system considering the effect of corrosion on the lining reinforcement. The aging effect due to corrosion of the reinforcement is taken into account by reducing the strength properties of the tunnel lining. Time-dependent fragility curves as a function of free-field Peak Ground Velocity (PGV) and service time t, are developed for minor, moderate and extensive damage states. Results show an overall increase of the seismic fragility for the deep tunnels over time, highlighting the important influence of aging effects on the performance of tunnels. The findings of this study provide an improved understanding of the response of tunnels in soft soils exposed to diverse hazards, and hence, facilitate the life-cycle seismic risk assessment and resilient designs of transport infrastructure.
