Investigation of an Accelerated Deterioration Method for Subsea Tunnel RC Linings via Electromigration and Its Associated Test Parameters

Appropriate accelerated deterioration methods are crucial for studying the deterioration behavior of reinforced concrete linings in subsea tunnels. To investigate the deterioration mechanisms of reinforced concrete (RC) structures in marine environments, this study employed the electromigration method to simulate accelerated chloride-induced corrosion of steel reinforcement. The results demonstrate that under a direct current (DC) electric field, chloride ions migrate directionally and accumulate on the side of the steel facing the chloride source, successfully inducing non-uniform corrosion features that closely resemble those in natural environments. The side facing chloride ingress exhibited severe corrosion and significant cross-sectional loss, while the shielded side remained largely intact. The experimental process clearly reveals that the applied electric field does not directly initiate corrosion of the steel reinforcement before chloride ions migrate to its surface. Furthermore, analysis of experimental parameters showed that symmetrical perforations on electrode plates are crucial for a uniform electric field, while perforation ratio and electrode–specimen distance have a minor influence. The average chloride penetration depths corresponding to electrode plate perforation areas of 5.5%, 15%, 25.5%, and 38.1% were measured as 1.63 cm, 1.67 cm, 1.57 cm, and 1.57 cm, respectively. This research confirms electromigration as an efficient and reliable technique for accelerated corrosion testing, providing a significant theoretical basis for assessing and predicting the long-term durability of marine engineering structures.