Soil Parameter Optimization of the NGI-ADP Constitutive Model for Bangkok Soft Clay

Abstract

This paper studies the NGI-ADP soil model, which can realistically simulate the anisotropic undrained stress strain responses and undrained shear strengths of clays. The model requires direct input parameters of undrained shear strengths and failure shear strains, including triaxial compression test, triaxial extension test and direct simple shear. However, parametric studies in this paper clearly show that trial-and-error testing of some input parameters is necessary in order to determine the optimal set of input parameters. The paper proposes the equations of anisotropic stress strain curves of this soil model and the technique of soil parameter optimization so that the optimal set of input parameters can be determined automatically and efficiently. The technique of soil parameter optimization is based on the statistical approach of least squares where proposed stress strain curves are used to compute model predictions. Finally, the proposed technique of soil parameter optimization of the NGI-ADP model is employed to determine the optimal set of input parameters for Bangkok soft clay.