A Modified Wedge-Prism Model for Calculating the Limit Support Pressure of a Shallow Shield Tunnel Face in Unsaturated Sandy Soil
Publication: International Journal of Geomechanics
Volume 24, Issue 10
Abstract
The limit support pressure significantly influences the stability of the shield tunnel face and deformation control during tunneling. Current research predominantly focuses on soils under dried or saturated conditions. However, unsaturated soils, which are more commonly encountered in engineering practice and widely distributed, have not been as extensively studied. Based on limit equilibrium theory, a modified analytical wedge-prism model is proposed in this paper to predict the limit support pressure acting on the shallow shield tunnel face in unsaturated sandy soil where the soil arching effect is considered. Taking advantage of finite-element software ABAQUS (version 2021), a series of numerical trapdoor tests are conducted first to study the failure behavior of unsaturated sandy soil. Then, by combining the rotation trajectory of major principal stress with the shear strength theory of unsaturated soil, the loosening earth pressure solution above the shallow trapdoor can be derived analytically. The limit support pressure can be finally obtained through a force equilibrium analysis of the wedge body. The accuracy of the proposed model is validated by comparing the calculated results with current model tests and numerical simulations. Parameter analysis results reveal that both the loosening earth pressure and limit support pressure initially decrease and then increase with the rising degree of soil saturation. A critical saturation point is identified where the loosening earth pressure and the limit support pressure reach their minimum values, attributed to the full development of the soil arching effect.
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Data Availability Statement
Some or all data, models, or codes that support the findings of this study are available from the corresponding author upon reasonable request. To be specific, all data that support all the figures in this paper can be provided by the corresponding author.
Acknowledgments
Financial support from the National Natural Science Foundation of China (41874067), the Innovative Funds Plan of Henan University of Technology (2022ZKCJ07), and the Commonweal Technology Project of Jinhua City (2023-4-037) is gratefully acknowledged.
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Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 24 • Issue 10 • October 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Dec 30, 2023
Accepted: Apr 29, 2024
Published online: Aug 8, 2024
Published in print: Oct 1, 2024
Discussion open until: Jan 8, 2025
ASCE Technical Topics:
- Continuum mechanics
- Dynamics (solid mechanics)
- Engineering fundamentals
- Engineering mechanics
- Geomechanics
- Geotechnical engineering
- Models (by type)
- Numerical models
- Pressure (type)
- Sandy soils
- Saturated soils
- Soft soils
- Soil analysis
- Soil dynamics
- Soil mechanics
- Soil pressure
- Soil properties
- Soils (by type)
- Solid mechanics
- Tunnels
- Unsaturated soils
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