富硫酸盐区域轨道交通系统面临杂散电流和盐腐蚀的双重影响，但此条件下的硫酸根离子传输行为和混凝土劣化机制尚不明确。为解决这一问题，设计了巧妙的硫酸根离子传输实验和细观尺度劈裂实验，重点考虑界面过渡区（ITZ）与水泥基体之间的差异。在杂散电流的影响下，ITZ在调节硫酸盐传输和混凝土力学破坏过程中起着关键作用，而骨料的曲折和阻挡作用几乎消失。这一现象被称为“杂散电流诱导的ITZ效应”。实验结果表明，由ITZ导致的硫酸根离子传输差异在1.90~2.31倍之间，劈裂强度差异则在1.56~1.64倍之间。通过劈裂实验与微秒级响应的粒子图像测速（PIV）技术的实时同步，揭示杂散电流诱导ITZ效应影响混凝土的力学失效机制。实验结果表明腐蚀混凝土加载破坏后的劈裂裂缝数量显著增加，而非沿中轴线分布，这与无杂散电流情况下的实验结果以及理想巴西圆盘实验结果显著不同。进一步地，本文构建了包含反应性和电扩散的硫酸根离子传质模型，将其嵌入有限元计算的结果与实验结果高度一致，验证了两者的可靠性和准确性。此外，还利用解析方法确定了应力场分布，揭示了腐蚀混凝土的裂纹扩展机制。与水泥基体相比，杂散电流导致ITZ中硫酸盐更富集、微观结构劣化更严重、厚度和孔隙率增加更快，这被认为是杂散电流诱导的ITZ效应的本质。

The rail transit in sulfate-rich areas faces the combined effects of stray current and salt corrosion; however, the sulfate ion transport and concrete degradation mechanisms under such conditions are still unclear. To address this issue, novel sulfate transport and mesoscale splitting tests were designed, with a focus on considering the differences between the interfacial transition zone (ITZ) and cement matrix. Under the influence of stray current, the ITZ played a pivotal role in regulating the transport and mechanical failure processes of sulfate attack, while the tortuous and blocking effects of aggregates almost disappeared. This phenomenon was termed the “stray current-induced ITZ effect.” The experimental data revealed that the difference in sulfate ion transport attributed to the ITZ ranged from 1.90 to 2.31 times, while the difference in splitting strength ranged from 1.56 to 1.64 times. Through the real-time synchronization of splitting experiments and microsecond-responsive particle image velocimetry (PIV) technology, the mechanical properties were exposed to the consequences of the stray current-induced ITZ effect. The number of splitting cracks in the concrete increased, rather than along the central axis, which was significantly different from the conditions without stray current and the ideal Brazilian disk test. Furthermore, a sulfate ion mass transfer model that incorporates reactivity and electrodiffusion was meticulously constructed. The embedded finite element calculation exhibited excellent agreement with the experimental results, indicating its reliability and accuracy. Additionally, the stress field was determined utilizing analytical methods, and the mechanism underlying crack propagation was successfully obtained. Compared to the cement matrix, a stray current led to more sulfates, more microstructure degradation, and greater increases in thickness and porosity in the ITZ, which was considered to be the essence of the stray current-induced ITZ effect.