Deformational responses of operated shield tunnel to extreme surcharge: a case study

A field case of operated shield tunnel disrupted by unexpected extreme surcharge in Shanghai is reported in this paper. The deformational responses of segmental lining, in terms of convergences, settlements and joint open width, are highlighted. The surcharge caused by unexpected dumped soils with a...

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Bibliographic Details
Published in:Structure and infrastructure engineering 2017-03, Vol.13 (3), p.345-360
Main Authors: Huang, Hongwei, Shao, Hua, Zhang, Dongming, Wang, Fei
Format: Article
Language:English
Subjects:
Convergence
Deformation
extreme surcharge
field case
Infrastructure
joint behaviour
lining deformation
Nonlinearity
Shield tunnels
Shields
Subway tunnels
Tunnels (transportation)
Workability
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Summary:A field case of operated shield tunnel disrupted by unexpected extreme surcharge in Shanghai is reported in this paper. The deformational responses of segmental lining, in terms of convergences, settlements and joint open width, are highlighted. The surcharge caused by unexpected dumped soils with a maximum height of 7 m is six times larger than the design value of surcharge. Three hundred and sixty segmental lining rings of the operated metro shield tunnel below this surcharge are severely affected. The measured horizontal convergence to outer-diameter ratio (ΔD/D out ) ranges from 16.6 to 35.7‰, which is far beyond the averaged value for normal condition, i.e. 5.1‰. The trend of tunnel deformation (e.g. horizontal convergence and settlement) varying with surcharge level is found to be significantly non-linear. Correspondingly, the longitudinal joints are also severely disrupted and have large open widths. The rubber packer for joint near-tunnel springline loses its function of waterproof due to the release of 6 mm pre-compressive deformation. The majority of steel bolts of joint near-tunnel crown have passed yield state, while some are fractured. However, the circumferential joints are found to be in a sound workability.
ISSN:1573-2479
1744-8980
DOI:10.1080/15732479.2016.1170156