This paper presents a case history of the developmental effect of a large-area excavation, 8 high-rise main buildings, a series of annex constructions, and ground overloaded building demolition on the deformation characteristics of an existing shield tunnel within Guangzhou Metro Line No. 1 in close proximity to the development. The shield tunnel lies in a sandy layer of the typical upper-soft and lower-hard strata in Guangzhou district, and the deformation of the tunnel has been monitored since the tunnel was put into operation. The monitoring results reveal that the adjacent construction induces an excessive tunnel settlement with a maximum of 14.4 mm and an excess tunnel displacement with a maximum of 5.2 mm, which are within the corresponding limitations of the codes for the safe operation of urban rail transit tunnels. While the station expansion project is being conducted beside the tunnels, a series of tunnel distresses, including large-area water seepage, spalling concrete blocks, and segmental cracks, are recorded. Our field monitoring data indicate that the tunnel is subjected to further vertical contraction and horizontal expansion due to the station expansion project, and a maximum tunnel flattening rate of 36.78% is detected. Furthermore, the tunnel linings are studied numerically and theoretically to obtain the limitations of tunnel deformation and discuss why tunnel distresses of water seepage, concrete spalling, and segmental cracking occur. Finally, on the basis of the analyses and discussions above, counteracting corrective measures, including compensation grouting soil strengthening and bonded steel plates, are adopted as exterior and interior strengthening methods, respectively, to eliminate further tunnel distresses and ensure safe operation. The lessons learned and summarized in this study may help prevent similar tunnel distresses from reoccurring in the future.

中文翻译：

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地铁盾构隧道邻近结构的变形特征与病害诊断。

本文介绍了广州地铁一号线大面积开挖，8座高层主楼，一系列附属建筑以及超载建筑物拆除对现有盾构隧道变形特性的发展影响的案例历史。 1紧邻开发区。盾构隧道位于广州地区典型的上，下，硬地层的沙层中，自隧道投入运营以来，一直在监测隧道的变形。监测结果表明，相邻建筑引起的隧道沉降最大为14.4 mm，隧道位移最大为5.2 mm，在城市轨道交通隧道安全运行规范的相应限制内。在隧道旁进行车站扩建工程时，记录了一系列隧道遇险情况，包括大面积渗水，混凝土块剥落和分段裂缝。我们的现场监测数据表明，由于车站的扩建工程，使隧道进一步竖向收缩和水平扩展，最大隧道展平率为36.78％。此外，对隧道衬砌进行了数值和理论研究，以获取隧道变形的局限性，并讨论了为什么会发生隧道渗水，混凝土剥落和分段裂缝的问题。最后，在上述分析和讨论的基础上，采取纠正措施，包括补偿性灌浆土壤加固和粘结钢板，分别采用外部和内部加固方法，以消除进一步的隧道困扰并确保安全运行。这项研究中总结的经验教训可能有助于防止将来再次发生类似的隧道事故。