摘   要：西北高盐渍地区预应力钢筒混凝土管（Prestressed concrete cylinder pipe，PCCP）保护层易发生Cl^-侵蚀，而目前关于长期轴向拉伸荷载与腐蚀环境耦合作用下的劣化机理研究仍较为薄弱，本文以立式浇筑PCCP混凝土保护层为研究对象，设计了一种卧式轴拉侵蚀试验装置，开展了不同荷载水平与侵蚀时间下的Cl^-扩散试验，探究了PCCP保护层Cl^-的侵蚀演化规律。结果表明：随着侵蚀时间的增加，Cl^-扩散深度和 Cl^-浓度均呈缓慢增大趋势；表面Cl-浓度与侵蚀时间呈非线性正相关关系，而Cl^-扩散系数与侵蚀时间呈非线性负相关关系；拉伸荷载会诱发混凝土内部微裂纹萌生、张开与扩展，裂纹延展方向与Cl^-扩散方向一致，这会加速Cl^-渗透进程。研究成果可为高盐渍地区PCCP保护层耐久性能设计、病害防控与服役寿命评估提供理论参考，也可为后续多因素耦合作用下耐久性能衰减模型的构建提供参考。

Abstract: In the high-salinity regions of Northwest China, the protective layer of prestressed concrete cylinder pipe (PCCP) is susceptible to Cl^- erosion. However, current research on the deterioration mechanisms under the coupling effect of long-term axial tensile loading and corrosive environments remains insufficient. In this study, the concrete cover of vertically cast PCCP is taken as the research object, and a horizontal axial tensile erosion testing device is designed. Chloride diffusion tests are conducted under various load levels and erosion times to investigate the Cl^- erosion evolution law in the PCCP protective layer. The results indicate that with increasing erosion time, both the Cl^- diffusion depth and Cl^- concentration exhibit a gradually increasing trend. The surface Cl^- concentration shows a nonlinear positive correlation with erosion time, whereas the Cl^- diffusion coefficient exhibits a nonlinear negative correlation with erosion time. Tensile loading induces the initiation, opening, and propagation of microcracks within the concrete, and the crack propagation direction aligns with the Cl^- diffusion direction, thereby accelerating the Cl^- penetration process. The findings can provide a theoretical reference for the durability design, disease prevention and control, and service life assessment of PCCP protective layers in high-salinity regions, and also offer a basis for the subsequent establishment of durability degradation models under multi-factor coupling conditions.