Simulations of 3-D drained behavior of normally consolidated clay using elastoplastic models
The simulative capabilities of two elastoplastic constitutive models under three-dimensional stress conditions are investigated. The two models employ different frameworks in predicting the stress-strain and strength of soils. One is the isotropic Dafalias-Kaliakin bounding surface model that employs a critical statebased failure criterion and uses an associated flow rule. The other model is the Single Hardening model which employs the Lade's failure criterion and assumes a nonassociated flow rule. The two models are used to simulate the stress-strain and strength behavior of six drained true triaxial tests with a constant mean effective stress but with different b-values on normally consolidated (NC) kaolin clay. The bounding surface model predicts overly small stress differences and large principal strains as compared to the experimental results. The Single Hardening model simulates the experimental results with much greater accuracy. It is found that the use of a realistic three-dimensional failure criterion and a non-associated flow rule better simulates the stress-strain and strength characteristics of NC clay under three dimensional stress conditions than the use of a critical state framework in conjunction with associated flow rule.