管片钢筋锈蚀对盾构隧道衬砌结构受力性能的影响研究

摘要

Under the long-term action of a water-soil load and ion-erosive environment, the mechanical behavior of a shield tunnel structure will be degenerated gradually. Based on the degeneration mechanism, a test regarding the corrosion of segment members under loading was carried out and the evolution law about the mechanical behaviors of segments under the combined action of a high water-soil load and erosive environment was analyzed. A decline model for the bending stiffness of the deteriorated segment was established. The structural mechanical behavior of the deteriorated segments of the Nanjing Weisan Road river-crossing tunnel was analyzed, with the results showing that:1) a high water-soil load creates favorable conditions for the rapid deterioration of the lining structure under an erosive environment; 2) in the process of deterioration of the segment, the occurrence and development of tensile cracks is accompanied by that of corrosion cracks, which presents the characteristics of non-uniform corrosion along the reinforcement;3) under a constant water-soil load, segment deformation develops in a non-linear way with an increase of the reinforcement corrosion rate, while the bending stiffness of the segment declines significantly with an increase of the corrosion rate; and 4) the structural mechanical behavior is represented by the evolution law of a structural stiffness decline, a deformation increase, a bending moment decrease and a basically unchanging axial force under the four structural deterioration conditions of 0%, 10%, 20% and 30%, respectively. The study results provide guidance and reference for precisely evaluating the long-term safety of a shield tunnel lining structure under the combined action of a water-soil load and erosive environment during the design reference period.%水土荷载与离子侵蚀环境的长期作用下，盾构隧道管片衬砌结构的受力性能将发生缓慢地退化。文章从盾构隧道结构受力性能衰退机理出发，开展承载管片构件锈蚀劣化试验，分析了高水土荷载与侵蚀环境联合作用下盾构隧道管片受力性能的衰退演化规律，提出了锈蚀劣化承载管片抗弯刚度衰减模型。以南京纬三路过江通道工程为例，分析了锈蚀劣化后管片衬砌结构的受力性能。研究结果表明：高水土荷载为侵蚀环境对衬砌结构的快速侵蚀弱化创造了条件；承载管片锈蚀劣化过程中，受拉裂纹与锈蚀裂纹相伴发生发展，顺筋方向体现出不均匀锈蚀的特点；水土荷载不变时，承载管片变形随钢筋锈蚀率的增大而非线性增长，构件刚度随锈蚀程度的增大而显著降低；结构锈蚀劣化程度分别为0%、10%、20%及30%四种工况下，结构受力体现出结构刚度降低、变形增大、弯矩减小、轴力水平基本维持不变的变化规律。研究成果可为准确评价设计基准期内，水土荷载与侵蚀环境联合作用下的盾构隧道衬砌结构的长期安全性能提供参考作用。