SANICLAY: A new simple anisotropic clay plasticity model

SANICLAY is a new simple anisotropic clay plasticity model that builds on a modification of an earlier model with an associated flow rule, in order to include simulations of softening response under undrained compression following Ko consolidation. Non-associativity is introduced by adopting a yield surface different than the plastic potential surface. Besides the isotropic hardening of the yield surface both surfaces evolve according to a combined distortional and rotational hardening rule, simulating the evolving anisotropy. Although built on the general premises of Critical State Soil Mechanics, the model incorporates a Critical State Line in the void ratio - mean effective stress space, which is a function of anisotropy. To facilitate the discussion, the model formulation is presented in the triaxial stress space. The SANICLAY is shown to provide successful simulation of the rate-independent behavior of normally consolidated sensitive clays, and to a satisfactory degree of accuracy of overconsolidated clays. The new model requires merely three more constants than those of the modified Cam clay model, all of which are easily calibrated from well established laboratory tests (two of them by explicit algebraic expressions) following a procedure presented on the basis of data for the Boston Blue clay. © 2007 Taylor & Francis Group