A hypoplastic model for clays with stiffness anisotropy
The implemented model has been published by Mašín (2014). This model is an anisotropic version of the general clay hypoplasticity model described thoroughly in Mašín (2013). Structure of the anisotropic stiffness matrix described in Mašín and Rott (2014). Structured-soil specific model features are described in Mašín (2007). The model can be used with the intergranular strain concept, its original formulation is in Niemunis and Herle (1997), enhanced formulation implemented is described in Mašín (2013). Most of the cited journal papers available here for free download in the form of PDF preprints.
Niemunis A and Herle I. (1997). Hypoplastic model for cohesionless soils with elastic strain range. Mechanics of Cohesive-Frictional Materials 2, 279-299.