在役隧道环境侵蚀下管片承载能力概率劣化模型

在役盾构隧道管片衬砌的承载能力劣化模型是隧道结构耐久性评价及科学养护的基础。以建立能考虑工程不确定性的钢筋混凝土管片概率承载能力劣化模型为目标，考虑隧道运营环境的主要侵蚀因子及管片衬砌的压弯受力特性，建立碳化侵蚀与氯离子侵蚀下管片主筋的锈蚀模型；考虑锈蚀管片中钢筋的截面面积损失以及钢筋-混凝土黏结滑移，以钢筋锈蚀率为媒介，构建锈蚀管片的时变抗弯及抗压承载能力计算模型；考虑衬砌管片抗弯及抗压承载能力的系统特性和相关性，基于概率统计理论，建立衬砌结构系统失效概率及可靠度的计算模型与方法。通过算例发现：管片抗弯承载能力劣化显著于抗压承载能力劣化，服役100年时，剩余抗弯承载能力和抗压承载能力分别约为初始值的30%和97%；结构抗力的均值与标准差均随结构劣化而减小；对管片的受弯模式，可靠度在95年时，拱顶、边墙及拱底部分位置不足规范要求，管片受压模式的可靠度（3.4~3.9）始终维持在较高水平；受弯和受压模式的相关性系数在0.93左右，管片结构的失效主要由抗弯承载能力不足引起。研究结果可为盾构隧道管片衬砌的耐久性设计及养护策略制定提供支持。

Probability Degradation Models of Bearing Capacity of Operating Tunnel Segments Under Environmental Erosions

The bearing capacity deterioration model of an operating shield tunnel segment lining is the foundation for the durability evaluation and scientific maintenance of tunnel structures. The aim of this study is to establish a probability deterioration model of the bearing capacity of reinforced concrete segments, considering engineering uncertainties. A corrosion model of the main bars of the segment exposed to carbonation and chloride ion erosion was established, considering the main erosion factors of the tunnel operating environment and the bending stress characteristics of the segment lining. The erosion rate of the main bars was adopted as the media, and time-varying calculation models of the flexural and compressive bearing capacities of the eroded segment were established, considering the cross-sectional area loss and steel-concrete bond slip. Based on the system performance and correlation between the segment lining flexural and compressive capacities, the model and methods for calculating the failure probability and reliability of the lining structure system were provided using a statistical probability theory. The segment flexural capacity exhibited a more significant deterioration than its compressive bearing capacity. The 100-year residual flexural and compressive capacities were approximately 30% and 97% of the original values, respectively. The mean and standard deviation of the structural resistance force decreases with structural deterioration. For the bending mode of the segment, the reliability of the tunnel crown, sidewalls, and bottom of the 95th operating year is insufficient compared with the code requirement. However, the reliability of the segment compression mode (3.4-3.9) is always maintained at a high level. The correlation coefficient of the bending and compression modes is approximately 0.93. The failure of the structural system of the segment is mainly attributed to inadequate bending strength. The research results are expected to guide the durability design and maintenance of shield tunnel segment linings.