Investigation on stress distribution and prestress loss model of prestressed anchor cables considering corrosion-induced debonding

Abstract

Corrosion can significantly impact the safety and stability of the entire structure by reducing the service life and load-bearing capacity of anchors. This study provides an in-depth examination of the effects of corrosion on prestressed anchor cables, covering the effects on the anchor cables themselves and the bond interface. The force characteristics and load transfer mechanisms within the anchorage structure were explored through a detailed analysis of the three key components: the anchor cable, the grout, and the surrounding rock. The distribution functions of axial force and interfacial shear stress considering the debonding of the anchor-grout interface were derived, and the prestressed corrosion damage model was further developed. Taking the anchoring project on the slopes in Nagasaki as an example, the stress distribution of anchor cables under different surrounding rock conditions was analyzed in depth. The results showed that the relative deformation of the grout and the surrounding rock decreases when the elasticity modulus of the surrounding rock increases, resulting in a reduced axial force in anchor cables and an increased interface shear stress. Thresholds exist for the effect of the total anchor length and radius on prestressing stability. When designing anchor structures in corrosive environments, there is no need to choose excessive anchor length or anchor radius to achieve better cost-effectiveness. In practical underground engineering, the force in anchor cables is transferred to the surrounding rock through the anchoring section, where the length of the anchorage section has a more direct impact on prestress transfer and stability.