Hydro-mechanical description of fractured porous media based on microporomechanics

• Totally micromechanics-based description of hydro-poroelastic behaviour of porous medium dispersed with micro-cracks.
• Multiscale model with closed-form continuum description of fractured rock involving very few parameters.
• Very robust in predicting hydraulic and poroelastic properties.

The fracture behaviour of cemented materials such as rock consisting of randomly distributed microcracks is addressed within a coupled physics and Hydro-Mechanical (HM) framework. Average-field theory is used to formulate a continuum description of such heterogeneous material based on observed microscale physical mechanisms in the fully saturated case. A representative elementary volume (REV) of the medium is considered over which governing field variables for both solid and liquid phases, including the underlying constitutive relations, are averaged based on a detailed description of the microstructure. Hence, coupled fluid flow and deformation mechanisms of an effective homogeneous porous medium can be ultimately described based on the micromechanical properties of both solid and fluid phases. The presence of heterogeneities in the form of distributed microcracks is described using an anisotropic formulation and considering a one-way coupled problem wherein fluid pressures impact on stress and strain fields, but not vice versa. The macroscopic behaviour is then described by relating the relevant macroscale quantities together using a suitable homogenization scheme. It is shown through various numerical examples that the model captures most of the salient underlying physics of HM behaviour of fractured porous medium due to the microporomechanical approach adopted in this study.