The settlement performance of an immersed tunnel in the Hong Kong–Zhuhai–Macau Bridge (HZMB) transportation project is described. The geological profile underlying the immersed tunnel is presented and the corresponding field monitoring system is introduced. The function of semi-rigid elements is analysed. The observed results related to longitudinal deformation patterns during construction (e.g. long-term settlement, differential settlement and structural behaviour) are described and analysed. Differential settlement occurred when there was a large variation in soil properties, at the joints of two adjacent elements and in different segments of the same element. Differential settlement occurred in both the longitudinal and transverse direction. During the operational period, permanent settlement was strongly related to back-silting. Tide loading and the immersion of adjacent elements may have caused transient settlement related to elastic deformation, but tide loading had less influence on the permanent settlement.

中文翻译：

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港珠澳大桥工程沉管隧道沉降特征

描述了港珠澳大桥（HZMB）交通工程沉管隧道的沉降性能。介绍了沉管隧道下方的地质剖面，并介绍了相应的现场监测系统。分析了半刚性单元的功能。描述和分析了与施工期间纵向变形模式相关的观测结果（例如长期沉降、差异沉降和结构行为）。当两个相邻单元的接缝处以及同一单元的不同部分的土壤性质发生较大变化时，就会发生不均匀沉降。纵向和横向均出现差异沉降。运营期永久沉降与回淤密切相关。潮汐荷载和相邻单元的浸没可能会引起与弹性变形相关的暂时沉降，但潮汐荷载对永久沉降的影响较小。