Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/27552

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Title
Finite element formulation and algorithms for unsaturated soils: part I - theory
Author/Creator
Sheng, Daichao;  Sloan, Scott W.;  Gens, Antonio;  Smith, David W.
Description
This paper presents a complete finite-element treatment for unsaturated soil problems. A new formulation of general constitutive equations for unsaturated soils is first presented. In the incremental stress-strain equations, the suction or the pore water pressure is treated as a strain variable instead of a stress variable. The global governing equations are derived in terms of displacement and pore water pressure. The discretized governing equations are then solved using an adaptive time-stepping scheme which automatically adjusts the time-step size so that the integration error in the displacements and pore pressures lies close to a specified tolerance. The non-linearity caused by suction-dependent plastic yielding, suction-dependent degree of saturation, and saturation-dependent permeability is treated in a similar way to the elastoplasticity. An explicit stress integration scheme is used to solve the constitutive stress-strain equations at the Gauss point level. The elastoplastic stiffness matrix in the Euler solution is evaluated using the suction as well as the stresses and hardening parameters at the start of the subincrement, while the elastoplastic matrix in the modified Euler solution is evaluated using the suction at the end of the subincrement. In addition, when applying subincrementation, the same rate is applied to all strain components including the suction.
Relation
International Journal For Numerical And Analytical Methods In Geomechanics Vol. 27, Issue 9, p. 745-765
Publisher Link
http://dx.doi.org/10.1002/nag.295
Date
2003
Publisher
John Wiley & Sons Ltd.
Keyword(s)
unsaturated soils;  finite element method;  constitutive model;  stress integration;  time integration
Resource Type
journal article
Identifier
http://hdl.handle.net/1959.13/27552
Identifier
ISSN:0363-9061
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Subject
"International Journal For Numerical And Analytical Methods In Geomechanics"
 
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