An inelastic homogenization framework for layered materials with planes of weakness

Shabnam J. Semnani and Joshua A. White

Computer Methods in Applied Mechanics and Engineering


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 constitutive 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.

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Comparison of model predictions with true triaxial test data from Mogi [RMRE 1979] for Chichibu schist. This metamorphic crystalline rock has a densely foliated structure, leading to different failure modes depending on the stress and loading orientation. Here, a constitutive framework is proposed to capture anistropy, plasticity, and discrete interface sliding inherent in such layered materials.