大断面盾构隧道管片接头力学行为研究

The segment joint is the key part of fabricated lining structure of shield tunnel. Whether the design is reasonable has relation to the safety of shield tunnel. In recent years, China has emerged in a large number of underwater shield tunnels with large cross-section，which are very sensitive to the joint structure and require scientific assessment and accurate values of joint mechanical parameters.The existing research theory and conclusion of segment joint have not been suitable for shield tunnels with large cross-section. In this study, theoretical analysis, numerical simulation and prototype test methods are used to research the micro mechanical behavior of segment joint. Effects of the detail joint surface structure on joint mechanical properties are analyzed. The more reasonable joint forms are discussed. The mechanical characteristics under different loads are investigated for the segment joint of shield tunnels with various cross-section size and structure type. The value range of joint bending stiffness is obtained. The calculation model of the whole segment ring that can consider three-dimensional nonlinear relation between bending stiffness and moment and axial force is established.The influences of joint bending stiffness on the internal force and deformation of the whole segment ring are studied.The joint mechanical properties are proved and the tunnel instability mechanism is disclosed when joint material is in nonlinear working state. The study results can provide theoretical basis for the optimization design of the segment lining of shield tunnels with large cross-section.

管片接头是盾构隧道衬砌结构的特殊关键部位，其设计的合理与否关系着盾构隧道的安全，近年来我国涌现出了大批大断面水下盾构隧道，这种大断面隧道整体结构对接头构造更加敏感，要求接头力学参数更能科学评估和准确取值，现有的管片接头研究理论和结论已经不适用于这种大断面盾构隧道。本研究采用理论分析、数值模拟和原型试验的方法对大断面盾构隧道管片接头的微观力学行为展开研究，分析接缝面复杂细部构造对接头力学性能的影响，探讨更加合理的管片接头形式；研究大断面盾构隧道几种典型断面大小、构造型式的管片接头在不同荷载作用下的力学特征，获得接头抗弯刚度的取值范围；建立考虑管片接头抗弯刚度-弯矩-轴力非线性关系的整环管片结构计算模型，研究接头抗弯刚度对整环管片衬砌内力和变形的影响；探明接头材料非线性工作状态下的力学特征，揭示接头材料非线性工作导致的隧道失稳机理.本研究旨在为大断面盾构隧道管片衬砌的优化设计提供理论依据。

管片接头作为盾构隧道管片衬砌结构的关键构造部位，其力学特征极大地影响着整个盾构隧道的力学性能，尤其对于目前大量出现的大断面盾构隧道，现有一般城市地铁盾构隧道管片接头的研究理论和结论已经不再适用，管片接头力学参数的明确成为大断面盾构隧道力学问题研究的前提。本项目主要围绕大断面盾构隧道管片接头展开研究，首先针对几种典型断面的盾构隧道，即一般城市地铁盾构隧道和大直径水下公路或铁路盾构隧道，采用三维数值模拟的方法对其管片接头抗弯力学性能进行研究，揭示常用几种典型断面大小、构造型式的管片接头在不同荷载作用下的力学特征，获取接头抗弯刚度的取值范围；然后以外径10.8m的大断面盾构隧道管片衬砌为研究对象，采用单一恒定接头抗弯刚度的壳-弹簧模型，探讨接头抗弯刚度对大断面盾构隧道管片衬砌结构内力的影响，建立考虑管片接头抗弯刚度-弯矩-轴力非线性关系的整环管片结构计算模型，精确管片衬砌内力的计算；最后针对地层条件相对较软弱的盾构隧道，采用非线性有限元分析方法研究管片接头对盾构隧道稳定性的影响，研制能够真实反应管片接头随弯矩增大逐渐张开的模拟方法，采用模型试验的方法实现对盾构隧道弹性工作阶段、带裂缝工作阶段、失稳破坏阶段的全过程模拟，分析接头抗弯刚度等对结构稳定性的影响规律，探明盾构隧道管片结构的失稳破坏性态。