Third M.I.T. Conference on Computational Fluid and Solid Mechanics June 14–17, 2005  

Modeling response of unsaturated silty sand in three-invariant stress space

L.R. Hoyos*,a, P. Arduinob
aUniversity of Texas at Arlington, Department of Civil and Environmental Engineering, Arlington, TX 76019, USA bUniversity of Washington, Department of Civil and Environmental Engineering, Seattle, WA 98195, USA

  Full Text
An implicit integration algorithm has been developed to simulate stress-strain response of unsaturated soil under controlled-suction multiaxial stress states. The algorithm supports numerical analyses in the π-plane using a mixed-control constitutive driver, along with a generalized cam-clay model, incorporating a third stress invariant, Lode angle θ, within a constant-suction scheme. True triaxial data (σ1 ≥ σ2 ≥ σ3 ) from constant- suction triaxial extension (TE), triaxial compression (TC), and simple shear (SS) tests, conducted on cubical specimens of silty sand, were used for tuning of the developed algorithm. The Willam-Warnke surface was adapted to the unsaturated case for simulation of soil response in three-invariant stress space (p: q: θ). Agreement between the observed and predicted soil responses highlight the potential of the developed algorithm for analyses of boundary-value problems involving unsaturated soil deposits.

Keywords:   Unsaturated soil; Matric suction; Constitutive modeling; Axis translation; True triaxial testing; Implicit integration; Deviatoric plane

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