Characteristics of deformation and defect of shield tunnel in coastal structured soil in China

Abstract

Shield tunnel is a type of linear underground structure assembled by lining segments, characterized with long joint, weak stiffness, and strict deformation control requirement. The situation of the long-term deformation and defect of the shield tunnel in soft ground in coastal area of China is severe, mainly attributed to the tunneling-induced ground consolidation, frozen cross passage, groundwater pumping, cyclic train load, and nearby construction. Shield tunnel is buried in ground, and the above factors could result in underlying ground settlement, overlying ground loading/unloading, and at-side ground unloading. As a result, the tunnel could suffer from different types of structural deformation and defect. Based upon the aforementioned different reasons, this study investigates the characteristics of the tunnel deformation and defect corresponding to the different types of ground stress change and deformation. It is found that tunneling-induced ground consolidation, frozen cross passage, groundwater pumping, and cyclic train load mainly contribute to the longitudinal differential settlement but negligible transverse convergence, associated with water leakages at circumferential joints. In comparison, surface surcharge and at-side unloading not only cause significant longitudinal differential deformation but also increase transverse lining internal forces, resulting in water leakages at circumferential joints, longitudinal lining concrete cracks and water leakages. Finally, nearby construction could strongly disturb the ground and cause the generation of excess pore-water pressure, making the shield tunnel deformation develops continuously after the nearby construction is completed.

Keywords

Shield tunnel / Long-term deformation / Transverse convergence / Longitudinal differential deformation / Defect

1 CRediT authorship contribution statement

Fanyan Meng: Writing - original draft, Software, Methodology, Formal analysis, Conceptualization. Bo Hu: Software, Methodology. Renpeng Chen: Writing - review & editing, Supervision, Resources, Funding acquisition. Hongzhan Cheng: Writing - review & editing, Formal analysis. Huaina Wu: Visualization, Conceptualization.

2 Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

3 Acknowledgement

The research is supported by funds from the National Natural Science Foundation of China (Grant Nos. 52378338, 51938005, 52090082, and 52108318), and Department of Science and Technology of Hunan Province (Grant No. 2021RC3043).

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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