Life-cycle reliability-based design and reliability updating of reinforced concrete shield tunnels in coastal regions

In this paper, a novel approach for life-cycle reliability-based design and reliability updating of?reinforced concrete (RC) shield tunnels in coastal regions has been developed. For new shield tunnels, a reliability-based durability design criterion to determine the concrete cover and concrete quality for preventing the deterioration of structural performance during the structural service life is proposed. For existing shield tunnels, an approach to update structural reliability is established based on Sequential Monte Carlo Simulation. Epistemic uncertainty associated with the structural performance prediction of existing shield tunnels can be reduced compared with that of new shield tunnels. In illustrative examples, durability design factors and maximum water to cement ratio for designing RC segment satisfying the target durability reliability are investigated. For existing RC shield tunnels, the effect of the observational deformation of segmental lining on the time-dependent failure probability is discussed.