Differential Settlement and Induced Structural Damage in a Cut-and-Cover Subway Tunnel in a Soft Deposit
Publication: Journal of Performance of Constructed Facilities
Volume 30, Issue 5
Abstract
This study investigated the differential settlement and induced structural damage in the west extension of Nanjing Metro Line 1. The minimum and maximum cumulative settlements measured over the course of four years of operation were 1 mm and 122 mm, respectively. Four settlement troughs in the longitudinal direction of the line, as well as a periodic variation of differential settlement between the stations and the tunnel, were observed. Approximately 10% of the vertical radius of curvature of the line violates the safety limit of 15,000 m, and three typical kinds of cracks (i.e., transverse cracks in the tunnel roof and in the track bed, and inclined cracks in the outer wall) and leakage have occurred. The differential settlement of the line was mainly caused by the nonuniform distribution of underlying soft soil. The periodic variation of differential settlement between the stations and tunnel was attributed to the structural characteristics and the seasonal variation in the groundwater level. The findings presented in this paper can provide a reference for controlling the differential settlement of tunnels constructed in soft deposits.
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Acknowledgments
Financial support for this research was provided by the National Natural Science Foundation of China (NSFC) through Grant Nos. 51478353 and 51008158. The authors are extremely grateful to the engineers and technical staff of Nanjing Metro Technology Consulting Ltd. and the Nanjing Institute of Surveying, Mapping, and Geotechnical Investigation Co., Ltd. for their field monitoring efforts. Support from the Nanjing Metro Co., Ltd. is also gratefully acknowledged.
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Published In
Journal of Performance of Constructed Facilities
Volume 30 • Issue 5 • October 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: May 6, 2015
Accepted: Dec 29, 2015
Published online: Mar 15, 2016
Discussion open until: Aug 15, 2016
Published in print: Oct 1, 2016
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