Improved Analytical Soil Arching Model for the Design of Piled Embankments
Publication: International Journal of Geomechanics
Volume 21, Issue 3
Abstract
Because analytical soil arching models are fundamental for the design of piled embankments, numerous soil arching models were proposed for this purpose. However, the results obtained from various soil arching models differ considerably, which may be due to the different assumptions caused by an incomplete understanding of soil arching behaviors. In this study, a series of two-dimensional (2D) discrete element method models were conducted to reveal the underlying mechanism for the mobilization of soil arching and its morphological characteristics. Then, an improved analytical soil arching model was developed, taking into account the mobilization state of soil arching, modifications to the soil arching height, and the corresponding load-uniformity coefficient of the stress acting on the subsoil. Finally, the feasibility of the present model was verified by comparing the results with the experimental data. The results showed that both the soil arching height and the load-transfer efficacy depend on the mobilization state of soil arching. The maximum soil arching height was found to be about 0.8 times that of pile clear spacing, in which the load-transfer efficacy reaches a peak. The present model in which the mobilization state of soil arching is taken into account could estimate the deformation and stress state of a piled embankment more accurately.
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Acknowledgments
This work was funded by the National Key R&D Program of China (No. 2016YFC0800200), the National Natural Science Foundation of China (NSFC) (Nos. 51708243, 51878313, and 52078236), and the China Postdoctoral Science Foundation (Nos. 2016M600595, 2018M632862, and 2018T110769). The authors would like to express their gratitude for these financial assistances.
Notation
The following symbols are used in this paper:
- a
- pile width;
- E
- load-transfer efficacy of embankment;
- Ecb
- load-transfer efficacy based on the critical state above piles;
- Ecrown
- load-transfer efficacy based on the critical state at the arching crown;
- Ef
- one-dimensional stiffness of the embankment fill;
- Es
- Young's modulus of subsoil;
- Esb
- one-dimensional stiffness of subsoil;
- f
- friction coefficient of the embankment fill;
- H
- embankment height;
- hs
- soil arching height;
- K0
- coefficient of earth pressure at rest;
- Kp
- coefficient of passive earth pressure;
- PL
- total load carried by cap beam;
- r
- radial distance of the embankment fill element;
- Sp
- settlement of the pile;
- Ss
- settlement of subsoil;
- s
- pile spacing;
- ts
- thickness of subsoil;
- α
- load-uniformity coefficient for the stress acting on subsoil;
- γ
- unit weight of the embankment fill;
- δi
- compression of the inner column upon the pile;
- δo
- compression of the outer column upon subsoil;
- Δs
- pile–subsoil relative displacement;
- Δsa
- pile–subsoil relative displacement calculated with the arching model;
- ɛ
- axial strain of foam rubber;
- μ
- Poisson’s ratio of subsoil;
- σi
- vertical stress just below the inner boundary of the arching crown;
- σo
- vertical stress acting on the outer column upon subsoil;
- σp
- stress acting on the pile;
- σpi
- vertical stress acting on the inner column upon the pile;
- σr
- radial stress of the embankment fill element;
- σrf
- stress acting on foam rubber;
- σs
- stress acting on subsoil;
- σu
- equivalent uniform stress acting on the subsoil;
- σθ
- tangential stress of the embankment fill element; and
- φmax
- peak secant angle of the embankment fill.
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Published In
International Journal of Geomechanics
Volume 21 • Issue 3 • March 2021
Copyright
© 2020 American Society of Civil Engineers.
History
Received: Nov 16, 2019
Accepted: Sep 29, 2020
Published online: Dec 16, 2020
Published in print: Mar 1, 2021
Discussion open until: May 16, 2021
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