Generalization of anisotropic constitutive models using transformed stress method

The generalization of anisotropic constitutive models is more complex than that of isotropic constitutive models. Using the g(θ) method to generalize the anisotropic constitutive models will result in the discontinuousness and concavity of yield surfaces. But the yield surfaces can be continuous and the critical state surfaces can consist with the adopted failure criterion if the transformed stress (TS) method is used. The modified Cam-clay model with initial stress-induced anisotropy is generalized using the TS method as an example. The proportionality constant and the stress gradient of the generalized model are defined, and the tangent stiffness matrix used in finite element analysis is given. It is seen from the comparison between the test data and the model predictions that the generalized anisotropic constitutive model using the TS method can reasonably describe the strength and deformation characteristics of the K₀-consolidation soils.