Integration of anisotropic modified Cam Clay model in finite element analysis: Formulation, validation, and application

Document Type

Article

Publication Date

12-1-2019

Abstract

The Dafalias’ [1] anisotropic modified Cam Clay model, proposed on the basis of the critical state theory, is one of the most widely used anisotropic elastoplastic constitutive models for clays, attributed mainly to its relative simplicity, yet still capable of capturing the essential features of the anisotropic soil behaviour. This paper develops an implicit integration algorithm for such anisotropic modified Cam Clay soil model, using the standard return mapping approach (elastic predictor-plastic corrector), to obtain the updated stresses and state parameters for given strain increments. It is found that the finite element formulation of the constitutive relationship essentially involves 13 simultaneous equations with 6 stress components σij and 7 state variables αij and pc′ as the basic unknowns to be solved. The integration algorithm developed for this model is thereafter implemented into the commercial program, ABAQUS, through the interface of the user defined material subroutine (UMAT). Numerical simulations have been conducted to analyze the undrained and drained cavity expansion problems as well as miniature piezocone penetration test for the purpose of validation, and to solve pile setup as the illustrative application of the developed computational solution. The predictions from the ABAQUS simulations are generally in excellent agreement with the available analytical/experimental results, which well demonstrates the accuracy and robustness of the proposed integration scheme. In addition, the numerical studies show the increase of the undrained shear strength of the soil around the pile hole as time progresses for the pile setup analysis.

Publication Source (Journal or Book title)

Computers and Geotechnics

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