The Incorporation of New Isotropic and Kinematic Hardening Rules in an Anisotropic Constitutive Model

The paper presents a new constitutive model to describe the mechanical behaviour of uncemented anisotropically consolidated clayey soils, by extending and improving previous models developed by the authors (Kavvadas 1982; Belokas & Kavvadas 2010) with respect to the anisotropic compression and the uniqueness of critical state. The model incorporates a rotated distorted ellipsoidal yield surface, a non-associated flow rule to reproduce zero total horizontal strains under K0 conditions and a new mixed hardening rule consisting of an isotropic part to control the evolution of the size of the yield surface and a rotationaldistortional part to describe the evolution of anisotropy. The model is capable of reproducing a) Intrinsic Compression Curves that depend on the degree of developed anisotropy and b) unique critical state conditions. The model capabilities are demonstrated through a series of numerical analyses.