弱抗力地层盾构隧道结构失稳破坏机理及稳定性分析模型研究

Due to the safe, environment-friendly and quick construction reasons, shield-driven tunnels have been widely applied in the urban rail transit network. In the past decades, a large amount of shield tunnels have been constructed and used. During the long-time service period, instability failure has been found in several shield tunnels, especially in the weak resistance strata. With the increment of service period, the micro-cracks existing in the segments (due to manufacture problem) are enlarged and propagated. The micro-crack propagation leads to the occurrence of macro-cracks in the reinforced concrete segments and segmental joints. With the macro-crack propagation, local instability failure happens in the segmental linings, which easily leads to the instability failure of the whole tunnel structure. In this research, literature review, theoretical analysis, model test and numerical analysis are carried out to establish a stability analysis numerical model for the segment linings in shield tunnels taken into account the stratum-structure interaction based on the damage revolution plasticity theory. Based on the proposed stability analysis model and the instability failure model test, a comprehensive study is carried out to investigate the stability revolution during elastic working stage, damage working stage and instability failure stage, to understand the instability reasons and thresholds, and to reveal the instability failure mechanism of the shield tunnel structure. The research findings are useful and applicable to control and optimize the tunnel structure stability, and will guarantee the operation safety of the shield tunnel during its design life-time.

由于盾构隧道具有安全性高、对环境扰动小以及掘进速度快等特点早已成为城市轨道交通网建设的首要选择。随着大量盾构隧道的建成使用，其长期的稳定性问题逐渐凸显出来。尤其是在具有触变性的弱抗力地层中，管片衬砌自身存在的微小裂缝随着运营时间增加而发生损伤演化，继而引发管片局部开裂，进而导致整体结构的失稳垮塌。本项研究拟采用资料调研、理论分析、室内试验与数值模拟相结合的方法，考虑地层与隧道结构相互作用，建立了盾构隧道管片衬砌结构基于塑性损伤理论的稳定性分析模型，针对弱抗力地层盾构隧道展开系统性的稳定性分析，探明承载状态下盾构隧道管片衬砌结构从弹性工作阶段、带裂缝损伤工作阶段至失稳破坏发展过程中稳定性态演变过程，揭示结构稳定性态变异的致因和阈值，揭示盾构隧道结构失稳破坏机理。并基于此，提出盾构隧道结构稳定性控制方法和指标，以保障盾构隧道在设计基准期内的营运安全。

盾构隧道具有安全性高和高掘进速度快等特点早已成为城市轨道交通网建设的首要选择。随着大量盾构隧道的建成使用，其长期的稳定性问题逐渐凸显出来。尤其是在具有触变性的弱抗力地层中，管片衬砌自身存在的微小裂缝随着运营时间增加而发生损伤演化，引发管片局部开裂，进而导致整体结构的失稳垮塌。本研究采用资料调研、理论分析、室内试验与数值模拟相结合的方法，考虑地层与隧道结构相互作用，建立了盾构隧道管片衬砌结构基于塑性损伤理论的稳定性分析模型，针对若抗力地层条件盾构隧道展开系统性的稳定性分析，探明承载状态下盾构隧道管片衬砌结构从弹性工作阶段、带裂缝损伤工作阶段至失稳破坏发展过程中稳定性态演变过程，揭示引起结构稳定性态变异的致因和阈值，揭示盾构隧道管片衬砌结构体系失稳破坏机理。并基于此，提出盾构隧道结构稳定性控制方法和指标，以保障盾构隧道在设计基准期内的营运安全。