Subsea shield tunnels usually serve in a typical corrosive marine environment. Under the action of chloride penetration and carbonization, tunnel lining segments are often damaged because of concrete strength loss and steel bar corrosion induced concrete cracking during their service life, which seriously degrades the service performance of the tunnels. A systematical experimental and numerical investigation into the performance degradation of subsea shield tunnel segments accounting for concrete strength loss and steel bar corrosion is presented in this paper. The study demonstrates that chloride penetration decreases the peak strength and elastic modulus of the segment concrete by 42% and 46.1%, respectively. The average of the ratio of dissipated energy to the total energy of dry concrete is much smaller than that of water saturated concrete and chlorine solution saturated concrete, and chloride penetration reduces the energy storage capacity of concrete, and the ability to resist damage is weakened. When steel bars corrode for 120 days, the outer cracks continue to extend, and the concrete around the inner steel bars just begin to crack initiation; when corrode for 20 years, the length of the inner cracks gradually exceeds that of the outer cracks, and the inner cracks initiating from different steel bars coalesce with each other and form a continuous failure surface, causing great serious damage to the segment. Due to the difference in concrete strength, for the outer layer, the evolution processes of steel bar corrosion-induced cracks show the characteristics of early initiation, slow propagation, and late coalescence, and those for the inner layer have the characteristics of late initiation, rapid propagation, and early coalescence. During the whole process the propagation speed of the inner and outer cracks appears to be fast first and then slow. Moreover, the study also illustrates that the final state of segment performance degradation after crack coalescence presents the characteristics of whole lamellar exfoliation of the concrete cover.

中文翻译：

---

考虑混凝土强度损失和钢筋腐蚀的海底盾构隧道段性能退化

海底盾构隧道通常在典型的腐蚀性海洋环境中使用。隧道衬砌管片在氯化物渗透和碳化作用下，在其使用寿命期间经常因混凝土强度损失和钢筋腐蚀引起混凝土开裂而损坏，严重降低了隧道的使用性能。本文对海底盾构隧道管片由于混凝土强度损失和钢筋腐蚀引起的性能退化进行了系统的实验和数值研究。研究表明，氯化物渗透使管片混凝土的峰值强度和弹性模量分别降低了 42% 和 46.1%。干混凝土耗散能量与总能量之比的平均值远小于水饱和混凝土和氯溶液饱和混凝土，氯离子渗透降低了混凝土的储能能力，抵抗破坏的能力减弱。钢筋锈蚀120天后，外层裂缝继续扩大，内层钢筋周围的混凝土才开始开裂；腐蚀20年时，内裂纹长度逐渐超过外裂纹长度，不同钢筋产生的内裂纹相互融合形成连续破坏面，对管片造成严重破坏。由于混凝土强度的不同，对于外层，钢筋腐蚀裂纹的演化过程呈现出早萌、慢扩展、晚聚结的特征，内层腐蚀裂纹的演化过程具有晚萌生、快扩展、早聚结的特点。在整个过程中，内外裂纹的扩展速度呈先快后慢。此外，研究还表明，裂缝合并后管片性能退化的最终状态呈现出混凝土保护层整体层状剥落的特征。在整个过程中，内外裂纹的扩展速度呈先快后慢。此外，研究还表明，裂缝合并后管片性能退化的最终状态呈现出混凝土保护层整体层状剥落的特征。在整个过程中，内外裂纹的扩展速度呈先快后慢。此外，研究还表明，裂缝合并后管片性能退化的最终状态呈现出混凝土保护层整体层状剥落的特征。