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...

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.