Investigating the mechanical responses and strengthening effects of surcharge-disturbed shield tunnels with varying cross-sections is crucial for ensuring the effectiveness of structural safety evaluations and treatments. This study introduces an elaborate modeling approach for segmental rings of three different sizes. Using calibrated finite element (FE) models and a proposed numerical simulation method for strengthening deformed segmental rings, the variations in surcharge-induced mechanical behaviors and strengthening effects in shield tunnels with typical cross-sections were analyzed. Based on these findings, safety classification standards and recommendations for selecting strengthening measures for shield tunnels with typical cross-sections are established. The results indicate that surcharge-disturbed shield tunnels with typical cross-sections exhibit certain variations in structural internal force levels and transmission characteristics, as well as in the timing of plastic hinge formation and joint mechanical response. Additionally, there are also commonalities in the overall deformation and damage mechanisms of the structures. For instance, the stable and accelerated development stages of segmental deformation are primarily driven by segment cracking, while the rapid development stage is triggered by both the surrounding stratum reaching passive earth pressure and the formation of structural plastic hinges. Accordingly, a safety classification standard for single-line shield tunnels with typical cross-sections is established. For a 6.2 m diameter tunnel, a steel plate-UHPC composite structure (SUCS) is recommended if spatial conditions permit, owing to its excellent interface properties. For a 6.7 m diameter tunnel, both SUCS and prefabricated UHPC slab (PUS) are preferred, provided that the layer thickness and interface measures are appropriately designed. For an 8.8 m diameter tunnel, EBSP, SUCS, and PUS are all viable options, although modifications to the conventional strengthening measures are necessary to enhance mechanical performance.

中文翻译：

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典型截面单线盾构隧道附加物诱导力学响应及加固效应的精细数值研究


研究不同截面的附加扰动盾构隧道的力学响应和加固效果对于确保结构安全评估和处理的有效性至关重要。本研究介绍了一种针对三种不同大小的节段环的复杂建模方法。使用标定的有限元 （FE） 模型和所提出的用于加固变形节段环的数值模拟方法，分析了典型截面盾构隧道中附加物诱导的力学行为和加固效果的变化。基于这些发现，建立了具有典型截面的盾构隧道的安全分类标准和选择加固措施的建议。结果表明，具有典型截面的附加扰动盾构隧道在结构内力水平和传递特性以及塑性铰形成和节理机械响应的时间方面表现出一定的变化。此外，结构的整体变形和损伤机制也存在共性。例如，管片变形的稳定和加速发展阶段主要由管片开裂驱动，而快速发展阶段则由周围地层达到被动土压力和结构塑性铰链的形成触发。因此，建立了具有典型截面的单线盾构隧道的安全分类标准。对于直径为 6.2 m 的隧道，如果空间条件允许，建议使用钢板-UHPC 复合结构 （SUCS），因为它具有出色的界面特性。对于 6.直径为 7 m 的隧道，首选 SUCS 和预制 UHPC 板 （PUS），前提是层厚和界面措施设计得当。对于直径为 8.8 m 的隧道，EBSP、SUCS 和 PUS 都是可行的选择，尽管需要修改常规加固措施以提高机械性能。