Effects of sustained load and reinforcement spacing on the evolution and spatial characteristics of corrosion damages in RC segmental specimens

Abstract

Because of the combined actions of sustained load and corrosive agents, premature steel corrosion and rapid material deterioration can be extensively observed in the reinforced concrete (RC) shield tunnels in an aggressive environment. Such a degradation accompanies with diverse corrosion damages in segmental lining, such as nonuniform steel corrosion and crisscrossed cracks on concrete surface, which shall be exacerbated due to congested steel arrangements and complex stress states in segment. In this paper, a corrosion-accelerated experiment on RC specimens in a tunnel segment was conducted by employing galvanostatic method and a designed loading system. Multiple rebars with different spacing distances were considered in two types of RC specimen. Deterioration damage evolution of RC specimens, including deterioration deformation and surface cracking patterns, has been investigated with an emphasis on the influence of sustained load and interaction of corroded rebars. Both visual inspection and distributed optical fiber sensing technology were applied to track the surface concrete cracking of bearing specimens. Meanwhile, the spatial variability of steel corrosion in bearing specimens was elaborated. The impacts of applied tensile load and reinforcement spacing on the spatial correlation of steel corrosion in longitudinal and transverse directions of rebars were experimentally illustrated. The experimental findings can help in improving the probabilistic model associated with nonuniform steel corrosion of several spaced rebars in tension and identifying the extent of corrosion damages in the load-bearing RC segments.