Failure mode of deteriorated concrete tunnel sections under subsidence and localised shear

Abstract

It is frequently reported that groundwater containing salt flowing into underground reinforced concrete structures results in steel reinforcement corrosion. However, little has been done to study the impact of such chloride-induced deterioration on structural performance when an external load acts on the underground structure, such as ground subsidence or the movement related to faults. In this study, structural experiments and finite-element analysis of the interaction between an underground structure and the ground were undertaken to clarify the failure modes and verify the numerical analysis. The failure behaviour of an underground structure with corroded steel subject to ground displacements was then examined analytically. It is concluded from the study that chloride-induced deterioration can impair the durability of an underground structure, making it difficult to maintain the inner space, and the failure mode is related to the location of the steel corrosion, which can change the direction of the shear zone in the peripheral ground.