大型水下盾构隧道双层衬砌相互作用机理研究

As the large underwater shield tunnels with deep-buried, super-long, large cross-section and high hydraulic pressure being more and more widely used, single-layer segment lining cannot satisfy the safety and durability any more, which results in the increasing demand of double-layer lining. At present, there is a controversy over the role of the shield tunnel secondary lining and a unified structure calculation theory on the double-layer lining used in shield tunnels has not yet formed. This project is proposed to conduct the systemic researches on the interaction mechanism between double layer linings of large underwater shield tunnels. The transverse and longitudinal mechanical properties and the accumulated damage characteristics about the large underwater shield tunnel double-layer lining are revealed. Then the interaction mechanism between double layer linings of large underwater shield tunnels is explored. The application conditions of the large underwater shield tunnel double-layer lining and the best time to carry out of the secondary lining are determined. The load distribution between the segment lining and the secondary lining is revealed. Finally the practical calculation method of the large underwater shield tunnel double-layer lining structure is established and the most optimal structure types and design parameters of the double-layer lining are achieved. Thus a complete structural design theory system of the large underwater tunnel double-layer lining is proposed. This research will provide a meaningful guidance to theoretical basis and practical methods in the structural design of the large underwater shield tunnel double-layer lining. At the same time, they will provide a reference for the maintenance and strengthening of existing shield tunnels.

大型水下盾构隧道日趋深埋化、超长化、大断面化以及高水压化，单层管片衬砌已难满足其对衬砌结构安全性和耐久性越来越高的要求，致使对双层衬砌的需求日益增加。然而，截至目前对于盾构隧道二次衬砌的作用在认识上仍存在偏差和争议，至今尚未形成统一的盾构隧道双层衬砌结构计算理论。本项目通过对大型水下盾构隧道双层衬砌相互作用机理问题开展系统研究，揭示大型水下盾构隧道双层衬砌结构横、纵向力学性能及累积损伤特性，探明管片衬砌与二次衬砌的相互作用机理；确定大型水下盾构隧道双层衬砌结构的使用条件和二次衬砌的最佳施做时机；揭示管片衬砌与二次衬砌之间的荷载分配规律，建立大型水下盾构隧道双层衬砌结构的实用计算方法，实现双层衬砌结构型式和设计参数的优化，进而形成完整的大型水下盾构隧道双层衬砌结构设计方法。项目研究成果将为大型水下盾构隧道双层衬砌结构设计提供理论依据和实用方法，同时可为既有盾构隧道的维护加固提供参考。

大型水下盾构隧道日趋深埋化、超长化、大断面化以及高水压化，单层管片衬砌已难满足其对衬砌结构安全性和耐久性越来越高的要求，致使对双层衬砌的需求日益增加。然而，截至目前对于盾构隧道二次衬砌的作用在认识上仍存在偏差和争议，至今尚未形成统一的盾构隧道双层衬砌结构计算理论。本项目采用理论分析、相似模型试验与有限元分析相结合的研究手段，系统研究了盾构隧道双层衬砌复合与叠合结构力学特征及其损伤特性、二次衬砌合理施作时机、管片与二次衬砌之间荷载传递及分配规律。主要取得如下研究成果:. 1）对盾构隧道双层衬砌管片与二次衬砌结构荷载分配模式进行研究，综合二次衬砌不同施作时机、接合面不同作用形式进行分析，探明了管片与二次衬砌结构之间的力学特性及双层衬砌截面内力分配比例随加载步变化趋势；. 2）分析了不同加载步管片与二次衬砌结构力学特征，探明复合与叠合结构管片与二次衬彻相互作用机理；. 3）根据大型水下盾构隧道管片衬砌力学性能的时间效应，对二次衬砌不同施作时机管片衬砌结构与二次衬砌结构之间受为特性、累积损伤特征等进行分析，探明了二次衬砌合理施作时机；. 4）建立了盾构隧道双层衬砌三维实体非连续接触模型，该模型可反映管片与二次衬砌混凝土损伤过程，同时考虑了管片钢筋对其力学性能的影响。. 项目研究成果将为大型水下盾构隧道双层衬砌结构设计提供理论依据和实用方法，同时可为既有盾构隧道的维护加固提供参考。