Coupled Directional Dilation–Damage Approach to Model the Cyclic-Undrained Response of Soft Clay under Pure Principal Stress Axes Rotation

Abstract

This study presents a directional constitutive model to predict the nonproportional cyclic behavior of undrained soft clay. A novel strategy consisting of a combination of directional dilation and the damage microplane model is used. Inherent cross-anisotropy is addressed via the modification of the integrated stress through an initial fabric tensor. The evolution of material microstructure is considered using the strain-dependent damage functions at the scale of microplanes. The variation of material stiffness is considered as a function of effective hydrostatic stress. The results were verified with available experimental data. The model accurately accounts for the effects of contributing factors, including the intermediate principal stress parameter.