考虑海蚀作用的水下盾构法隧道地震破坏机理及抗减震措施研究

With the rapid development of economy in coastal areas and the increasing demands for traffic infrastructure across river and sea, a large number of underwater shield tunnels are going to be constructed for highways, railways and subway in marine areas. These tunnels are always built in offshore complex geological ground, suffering long-term erosion of the marine environment, and have to face the threat of strong earthquakes at any time, so their lining structures are always in great risk of damage. This research considered the feature of underwater shield tunnel in complex marine environment, is conducted against the seismic behavior, seismic failure mechanism and aseismic measures for corroded and deteriorated lining structure suffering marine erosion. It starts from the deterioration characteristics and structural damage evolution of lining structure for underwater shield tunnel, the dynamic amplification effect, structural damage evolution mechanism will be studied under seismic vibration, then the damage mutation mechanism of corroded lining structure in different corrosion degree will be revealed. The study will also try to clarify the seismic dynamic response and failure mechanism of corroded single segmental lining and double-layer lining structure (which consists of corroded single segment lining and new-built secondary lining) under different corrosion state and earthquake intensity. Nevertheless, based on the seismic performance of different corrosion state, the deteriorated state partition of corrosion lining structure will be established. Then the aseismic measures and reinforcement measures can be developed according to the deteriorated state of corroded lining structure, which can guarantee the durability and long-term operation safety of underwater shield tunnel under marine environment.

随着我国沿海地区经济的发展和跨江海交通需求的增长，海域公路、铁路、城市地铁水下盾构隧道日益兴建。这些隧道处于近海复杂地质地层之中、长期遭受海洋环境侵蚀，并随时面临强震的威胁，发生结构破坏的风险极大。本项研究结合海域复杂环境水下盾构隧道特点，针对遭受海蚀作用的既受腐蚀衬砌结构的抗震性能、破坏机理与抗减震措施开展研究，从海蚀作用下水下盾构隧道衬砌结构的腐蚀劣化特征与损伤演化规律出发，研究既受腐蚀衬砌结构损伤在地震作用下的放大效应与演化机理，揭示地震作用下既受腐蚀衬砌结构的损伤变异机制；探明既受腐蚀单层管片衬砌结构、既受腐蚀单层管片衬砌+新筑二衬结构等在不同锈蚀状态、不同地震强度下的动力响应特性与破坏机理；并基于不同腐蚀状态的结构抗震性能，建立既受腐蚀衬砌结构的劣化状态分区，开发不同劣化状态下既受腐蚀盾构隧道衬砌结构的加固处理与抗减震处置措施，以保障海域水下盾构隧道衬砌结构的耐久与长期运营安全。

本项目结合海域复杂环境水下盾构隧道特点，针对遭受海蚀作用的既受腐蚀衬砌结构的抗震性能、破坏机理与抗减震措施开展了系统研究。首先，调研总结了海蚀环境下盾构隧道常见病害类型与特征，分析了盾构隧道耐久性问题的诱因。其次，采用理论分析、数值模拟等手段构建了考虑压力渗透作用的腐蚀离子在衬砌混凝土中的对流—弥散理论解析方程，合理表征了腐蚀离子介质侵蚀的时间-空间演变规律，探明了荷载与侵蚀环境耦合作用下管片结构侵蚀劣化的变化规律以及纤维对氯离子传输规律的影响，在此基础上，针对管片衬砌开展电化学快速腐蚀试验探明了海蚀作用下水下盾构隧道衬砌结构损伤演化规律，揭示了腐蚀管片衬砌结构的损伤变异机制。第三，开展振动台模型试验并结合动力时程分析，探明了跨海盾构隧道在腐蚀单层衬砌与增设二衬后构成双层衬砌结构下的地震响应特征、损伤发展规律与破坏过程。最后，开展动力时程分析探明了砂土地层、软土地层、地震波入射方式与地基加固对海蚀环境盾构隧道腐蚀管片衬砌地震响应的影响，提出了管片结构加固与地基加固的范围。在管片耐久性保障措施方面，考虑到纤维可提高盾构隧道钢筋混凝土管片的强度和耐久性，对海蚀环境下双掺钢纤维、聚丙烯纤维的钢筋混凝土管片开展锈蚀试验，探明了双掺钢纤维及聚丙烯纤维对不同腐蚀劣化状态下管片内力、形变、裂纹扩展以及破坏形态的影响规律，明确了不同腐蚀劣化阶段采用双掺聚丙烯纤维及钢纤维加固腐蚀劣化管片的效果。研究成果直接应用于广深港高速铁路狮子洋隧道、厦门地铁2号线、3号线跨海盾构隧道、以及佛莞城际铁路狮子洋隧道结构分析与管片设计中，并可为类似近海水下盾构隧道衬砌结构的耐久设计与长期运营安全提供重要参考。