  Many geologic materials have a composite structure, in which macroscopic
mechanical behavior is determined by the properties, shape, and heterogeneous
distribution of individual constituents. In particular, sedimentary rocks
commonly exhibit a layered microstructure, with distinct bedding planes that
can also form planes of weakness. In this work, we present a homogenization
framework for modeling inelastic layered media. The proposed constitutive model
allows for distinct micro-constitutive laws for each layer, explicit
representation of layer distributions, as well as incorporation of imperfect
bonding at the interface between adjacent layers. No a priori assumptions are
needed regarding the specific consitutive models used for the layers and
interfaces, providing significant modeling flexibility. The overall framework
provides a simple and physically-motivated way of defining anisotropic material
behavior as an emergent property of the layered microstructure. The model is
calibrated using triaxial and true-triaxial experimental data to demonstrate
its ability to describe anisotropic deformation and multiple modes of failure.
