  In this paper, the Combined Finite-Discrete Element Method (FDEM) has been
applied to analyze the deformation of anisotropic geomaterials. In the most
general case geomaterials are both non-homogeneous and non-isotropic. With the
aim of addressing anisotropic material problems, improved 2D FDEM formulations
have been developed. These formulations feature the unified hypo-hyper elastic
approach combined with a multiplicative decomposition-based selective
integration for volumetric and shear deformation modes. This approach is
significantly different from the co-rotational formulations typically
encountered in finite element codes. Unlike the co-rotational formulation, the
multiplicative decomposition-based formulation naturally decomposes deformation
into translation, rotation, plastic stretches, elastic stretches, volumetric
stretches, shear stretches, etc. This approach can be implemented for a whole
family of finite elements from solids to shells and membranes. This novel 2D
FDEM based material formulation was designed in such a way that the anisotropic
properties of the solid can be specified in a cell by cell basis, therefore
enabling the user to seed these anisotropic properties following any type of
spatial variation, for example, following a curvilinear path. In addition, due
to the selective integration, there are no problems with volumetric or shear
locking with any type of finite element employed.
