Plane Strain Simplified Analysis of Consolidation of a Foundation Penetrated by Concrete-Cored Gravel Columns
Publication: International Journal of Geomechanics
Volume 23, Issue 3
Abstract
The consolidation solutions of the foundation penetrated by the concrete-cored gravel (CCG) columns have been proposed based on a single-column model under the axisymmetric condition. A CCG column consists of a precast concrete pile inserted at the center of sand or gravel materials. Numerical modeling is commonly adopted for multicolumn field applications. Converting the axisymmetric unit cell into the plane strain model saves computation load and numerical simulation time. This study proposed a plane strain conversion method for the foundation penetrated by CCG columns. The plane strain conversion goes through a geometric transformation, stiffness equivalence, and consolidation equivalence. The consolidation equivalence is conducted by equating the consolidation degree at any depth of the plane strain model to that of the axisymmetric model. The penetration effect of the converted inner wall is used to modify the equal strain assumption of the plane strain model. The validity of the proposed method is examined by comparing it with 3D numerical simulation results and the field data from an embankment case history. The comparison reveals that the proposed plane strain conversion method enables the numerical simulation of the CCG column-reinforced foundation to be handled easily and largely saves the computation resources.
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Acknowledgments
The authors appreciate the financial support provided by Shanghai Science and Technology Development Funds (Grant Nos. 22ZR1466600) and the National Natural Science Foundation of China (NSFC) (Grant Nos. 41972272 and 41772281).
Notation
The following symbols are used in this paper:
- Ap, As, Aw
- cross-sectional areas of the inner pile, subsoil, and gravel column, respectively;
- B, bp, bw
- half-widths of influence area, core wall, and gravel wall, respectively;
- b
- half-width of the strip footing;
- Ec0
- deformation modulus of cushion;
- Ecom,a, Ecom,p
- composite moduli of the foundation in the axisymmetric and plane strain models, respectively;
- Ep,a, Ep,p
- moduli of the axisymmetric core pile and plane strain core wall, respectively;
- ,
- equivalent moduli of the axisymmetric core pile and plane strain core wall;
- Es, Ew
- moduli of subsoil and gravel column, respectively;
- H
- column length, equivalent to the reinforced layer’s thickness;
- kh,a, ks,a, kw,a
- radial permeability coefficients of the undisturbed zone, smear zone, and granular column, respectively, in the axisymmetric model;
- kh,p, ks,p, kw,p
- horizontal permeability coefficients of the undisturbed zone, smear zone, and granular wall, respectively, in the plane strain model;
- ma, na
- radius ratio of the core pile to gravel column and influence area to smear zone, respectively, in the axisymmetric model;
- mp, np
- half-width ratio of the core wall to gravel wall and influence area to smear zone, respectively, in the plane strain model;
- pa, pp
- vertical stresses undertaken by the core pile and inner wall, respectively;
- ps, pw
- vertical stresses undertaken by the gravel wall and subsoil, respectively, in the plane strain model;
- re, rp, rw
- radii of the radial influence area, core pile, and smear zone, respectively;
- sa
- upward piercing scale of the inner wall;
- sp, ss
- compression volumes of the inner wall and subsoil, respectively;
- un,a, um,a
- excess pore-water pressures of undisturbed and smear zones, respectively, in the axisymmetric model;
- ,
- average excess pore-water pressures of the composite foundation and subsoil, respectively, in the axisymmetric model;
- uw,p
- excess pore-water pressure of the gravel wall;
- ,
- average excess pore-water pressures of the composite foundation and subsoil, respectively, in the plane strain model;
- γw
- unit weight of water;
- vc
- Poisson’s ratio of cushion; and
- ɛv
- volumetric strain.
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Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 23 • Issue 3 • March 2023
Copyright
© 2022 American Society of Civil Engineers.
History
Received: May 11, 2022
Accepted: Sep 7, 2022
Published online: Dec 26, 2022
Published in print: Mar 1, 2023
Discussion open until: May 26, 2023
ASCE Technical Topics:
- Computer models
- Concrete
- Consolidated soils
- Consolidation (material)
- Engineering fundamentals
- Engineering materials (by type)
- Foundation settlement
- Foundations
- Geomechanics
- Geotechnical engineering
- Gravels
- Infrastructure
- Material mechanics
- Materials characterization
- Materials engineering
- Models (by type)
- Numerical models
- Pavements
- Plane strain
- Soil mechanics
- Soils (by type)
- Strain
- Transportation engineering
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