海底水下盾构法隧道衬砌结构的性能衰退演化机理

With the rapid development of economy in coastal areas in China, the traffic demand across straits and bays is increasing. Large subsea tunnel will become an important means to pass through the waters barrier. The construction of world-class large subsea tunnels, such as Qiongzhou Channel Tunnel, Hangzhou Bay Tunnel and Bohai Channel Tunnel, will be accomplished in the near future. In this research, information investigation,theoretical analysis, numerical simulation, electrochemical corrosion tests and model tests will be carried out. And it includes: degradation characteristics and mechanical properties of concrete corrosion; behavior of segmental joint under different corrosion deterioration degree; mechanical characteristics of segmental lining structure under different corrosion deterioration degree, loading condition, and different assembly methods. The results are expected to prove up the law of structure behavior's deterioration of subsea shield tunnel under the combined effects of the erosion environment and loading environment,and reveal the mutation mechanism and threshold of mechanical properties of segmental lining structure during the development of corrosion, cracking, and instability until the catastrophic collapse. Based on the above results, recommendations and indicators will be proposed against the structural system design and performance evaluation, in order to make sure the structure safety of subsea shield tunnel in the long-term operation stage.

随着国民经济的发展和沿海地区经济建设步伐的加快，跨越海峡和海湾的交通需求与日俱增，海底隧道必将成为我国今后跨越海湾、海峡等水域阻隔的重要手段，渤海湾跨海工程、杭州湾海湾工程、琼州海峡跨海工程等世界级大型海底隧道的建设即将开展。本项研究采用资料调研、理论分析、数值仿真和电化学腐蚀试验、室内模型实验相结合的方法，研究不同环境条件下海底盾构隧道管片混凝土腐蚀劣化特征与性能、不同腐蚀劣化程度下管片接头的力学性能，以及不同腐蚀劣化程度、不同荷载条件、不同拼装方式下海底盾构隧道管片结构的受力与形变特征，旨在探明海底侵蚀环境与荷载环境联合作用下管片衬砌结构力学性能的衰退、演化规律，揭示高水压条件下管片结构腐蚀、开裂、失稳直至灾变溃损的发生发展过程中受力性能的变异机制与阈值，并基于此对海底盾构隧道管片结构体系的设计与性能评价提出建议和指标，以保障海底盾构隧道衬砌结构的长期安全性。

本项目以海底水下盾构隧道管片衬砌结构为主要研究对象，采用资料调研、理论分析、数值仿真和电化学腐蚀试验、室内模型实验相结合的方法，针对结构受力性能的衰退演化过程与机理开展了系统研究。调研了跨江越海水下盾构隧道耐久性特征，确立了盾构隧道耐久性主要影响因素；开展了钢筋混凝土室内加速锈蚀及力学加载试验，揭示了钢筋锈蚀引起海底水下盾构隧道材料的劣化机理与劣化过程。根据室内加速锈蚀试验结果建立了基于弹性模量衰减模型的混凝土时效损伤变量，推导了混凝土材料损伤演化模型。采用数值分析及理论分析等研究手段，分析了腐蚀劣化管片接头的抗弯性能，揭示了腐蚀劣化隧道衬砌结构耐久性能及承载能力退化规律，分析了管片接头及自身缺陷等腐蚀劣化对管片衬砌结构力学性能的影响，构建了盾构隧道管片衬砌结构性能劣化计算模型。通过考虑腐蚀劣化效应的管片衬砌结构相似模型试验，研究了侵蚀环境与荷载环境联合作用下管片衬砌结构力学性能的衰退演化规律，探明了不同腐蚀劣化区域、不同荷载条件、不同拼装方式下海底盾构隧道管片结构的受力与形变特征，揭示了腐蚀劣化管片结构开裂、失稳破坏发生发展过程中受力性能的变异过程与阈值。