Unified Expression of Rotational Hardening in Clay Plasticity

Abstract

Rotational hardening is the constitutive ingredient of clay plasticity models that allows rotation of the yield surface in stress space to simulate, more realistically than isotropic models, the stress-strain response under different loading conditions. Based on well-known rotational hardening rules and extensive experimental results, a new unified expression of rotational hardening is proposed in this work, in which the parameters of the unified expression can be determined directly. The proposed rotational hardening expression was imported into a clay model and adopted to simulate the stress-strain behavior of different clays. The simulated results and the experimental results were compared to analyze the influence of the equilibrium values on the stress-strain behaviors. The comparisons show that the constitutive model with the proposed rotational hardening rule had good predictive capability for triaxial tests under different loading paths.