Field investigations were conducted to assess the corrosion status of reinforcements in the underground metro tunnels built between 1980 and 2006. The carbonation depth, half-cell potential, and concrete resistivity were measured on-site, and the chloride profile of cored specimens was analyzed in the laboratory. A theoretical analysis was conducted based on Nernst equation and Butler-Volmer equation. The nature of corrosion potential (half-cell potential) and its relationship with corrosion rate in different corrosion status were revealed. The impact of electric coupling in localized corrosion and macrocell corrosion was also analyzed. Connecting the theoretical analysis with the test results, the drop of the half-cell potential that occurred near the NaCl crystallization on some tunnel segments can indicate the presence of chloride-induced corrosion. However, for the segments showing damp patches and relatively low resistivity, it will be challenging to assess the corrosion status based simply on the half-cell potential due to the impact of electric coupling. The corrosion assessment in similar environments should be conducted carefully with the determination of corrosion sources and considering the impact of concrete mix proportion and electric coupling.

进行了现场调查，以评估1980年至2006年之间修建的地下地铁隧道中钢筋的腐蚀状况。现场测量了碳化深度，半电池电位和混凝土电阻率，并分析了带芯标本的氯化物分布。实验室。基于能斯特方程和巴特勒-沃尔默方程进行了理论分析。揭示了在不同腐蚀状态下腐蚀电位（半电池电位）的性质及其与腐蚀速率的关系。还分析了电耦合对局部腐蚀和大单元腐蚀的影响。将理论分析与测试结果联系起来，在某些隧道段上，NaCl结晶附近发生的半电池电位下降可能表明存在氯化物诱导的腐蚀。然而，由于电耦合的影响，对于显示出湿斑和相对低电阻率的线段，仅基于半电池电势来评估腐蚀状态将具有挑战性。在确定类似腐蚀环境下的腐蚀时，应仔细确定腐蚀源，并考虑混凝土配合比和电耦合的影响。