Evaluation and Optimization of the Corner Effect of a Deep Foundation Pit Adjacent to a Subway Tunnel
Publication: International Journal of Geomechanics
Volume 24, Issue 9
Abstract
The prevailing design methodology for foundation pit support structures conventionally treats the pit cross section as a two-dimensional plane, facilitating the computation of soil and water pressures acting upon the retaining structure. Regrettably, this conventional approach tends to overlook the critical corner effect, particularly when the foundation pit is in proximity to a subway tunnel, where the nuanced nature of this corner effect remains indeterminate. Consequently, this research is directed toward an in-depth investigation of a deep foundation pit contiguous to a subway tunnel. A systematic evaluation and optimization of the corner effect pertaining to the deep foundation pit are undertaken through a combination of comprehensive field monitoring and simulation methodologies. The results show that a substantial mitigation in the deformation of the supporting structure, settlements of the ground surface and adjacent buildings, as well as the displacement of the subway tunnel, were achieved through a consideration of the corner effect. Notably, the ameliorative impact of adjacent buildings on the corner effect is observed. Further scrutiny reveals that the supporting structure within a distance of 12 m from the pit corner is most susceptible to the corner effect, as evidenced by a plane strain ratio (PSR) falling below 0.8. Beyond a spatial threshold of 20 m, the PSR attains a value of 1.0, indicative of a negligible corner effect and the foundation pit section existing in a plane strain state. The adjustment of pile length or diameter based on the PSR emerges as a viable strategy that can realize the construction cost optimization on the premise of ensuring the stability of the foundation pit. The impact of pile diameter variation is paramount, corresponding to a reduction in the range of PSR values below 0.8 from 12 m to 9.8 m. The corner effect is significantly diminished.
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Data Availability Statement
All the data and models that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
The authors gratefully acknowledge the financial support provided by the Natural Science Foundation of Jiangsu Province (BK20220356), and the Opening Fund of the Key Laboratory of Geohazard Prevention of Hilly Mountains, Ministry of Natural Resources (Fu-jian Key Laboratory of Geohazard Prevention) (FJKLGH2023K005)
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© 2024 American Society of Civil Engineers.
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Received: Aug 18, 2023
Accepted: Feb 13, 2024
Published online: Jun 17, 2024
Published in print: Sep 1, 2024
Discussion open until: Nov 17, 2024
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