大直径盾构隧道在软土地层中面临着结构性能和维护效率的双重挑战。为解决这一问题，通过理论分析和数值模拟，提出了一种创新的预制中隔墙（precast middle partition wall, PMPW）设计方案，重点研究其在超载条件下的力学行为演化规律。研究结合有限元软件构建三维结构模型，系统地分析了结构从“接触前”到“接触后”的全过程响应特征。结果表明，基于6.88 cm顶部间隙的PMPW设计实现了结构柔-刚转变的有效调控，接头性能分析揭示了顶部楔形片与相邻管片界面在低轴力（3 000 ~ 4 000 kN）和高弯矩（约800 kN·m）组合下最易发生损伤。进一步研究发现，弧形构件较中隔墙更易在初始阶段出现损伤。基于此，研究提出了包含超高性能混凝土（ultra-high performance concrete, UHPC）局部增强的性能提升方案，试验结果表明该方案可使预制构件变形抗力提高20% ~ 60%。研究成果为大直径盾构隧道在复杂地质条件下的设计与施工提供了理论依据与工程指导。

In order to address the challenges of structural performance and maintenance efficiency in large-diameter shield tunnels within soft soil stratum, an innovative PMPW (precast middle partition wall) design was investigated through theoretical analysis and numerical simulation. A three-dimensional structural model was established using finite element software, and the mechanical behavior evolution under surcharge conditions was systematically analyzed throughout the "pre-contact" to "post-contact" phases. The results show that a 6.88 cm top gap in the PMPW design was found to effectively control the flexible-rigid transition of the structure. The interface between the top wedge segment and adjacent segments was identified as most susceptible to damage under the combination of low axial force (3 000 ~ 4 000 kN) and high bending moment (approximately 800 kN·m). Arc components were observed to be more prone to initial damage compared to middle partition walls. A performance enhancement scheme incorporating local UHPC (ultra-high performance concrete) reinforcement was proposed and tested. It is concluded that the proposed scheme could improve the deformation resistance of precast components by 20% ~ 60%, providing theoretical foundation and engineering guidance for the design and construction of large-diameter shield tunnels in complex geological conditions.