  Shale, like many other sedimentary rocks, is typically heterogeneous,
anisotropic, and is characterized by partial alignment of anisotropic clay
minerals and naturally formed bedding planes. In this study, a micromechanical
framework based on the Lattice Discrete Particle Model (LDPM) is formulated to
capture these features. Material anisotropy is introduced through an
approximated geometric description of shale internal structure, which includes
representation of material property variation with orientation and explicit
modeling of parallel lamination. The model is calibrated by carrying out
numerical simulations to match various experimental data, including the ones
relevant to elastic properties, Brazilian tensile strength, and unconfined
compressive strength. Furthermore, parametric study is performed to investigate
the relationship between the mesoscale parameters and the macroscopic
properties. It is shown that the dependence of the elastic stiffness, strength,
and failure mode on loading orientation can be captured successfully. Finally,
a homogenization approach based on the asymptotic expansion of field variables
is applied to upscale the proposed micromechanical model, and the properties of
the homogenized model are analyzed.
