Shear and compaction bands in porous rocks with a micromechanics-inspired non-local elastoplastic model

• A novel approach is developed for modeling shear and compaction bands in porous rocks; • A micromechanics-inspired constitutive model is proposed by incorporating various microstructural evolution mechanisms; • A novel non-local formulation is proposed by considering the interaction effect of porosity distribution; • The proposed model depicts the main aspects of mechanical responses of porous rocks and related microstructural evolution; • The proposed approach describes well the various scenarios of shear and compaction bands under different confining pressures. This study develops a novel approach for modeling shear and compaction bands in porous rock-like materials. A micromechanics-inspired constitutive model is first formulated to describe the fundamental mechanical response of porous rocks by incorporating the evolution of microstructure during plastic deformation. The novel non-local formulation is based on the interaction effect of spatial porosity distribution. Within this approach, the void and crack nucleation drives the shear deformation and localization, while the pore collapse controls the volumetric compaction and localization. The new model is implemented in the standard ABAQUS platform, providing a robust tool for investigating the formation of shear-compaction bands under various loading conditions. The results demonstrate that the proposed model accurately reproduces the transition of macroscopic pressure-sensitive plastic behavior from being dominated by pore and crack nucleation to pore collapse as confining pressure increases, thereby correctly capturing the brittle-ductile transition in the mechanical behavior of porous rocks. The model successfully captures the transition from shear bands to compaction bands under varying confining pressures, along with the associated microstructural evolution. During shear band formation, softening behavior driven by pore and crack nucleation dominates within the band, while the region outside the band undergoes elastic unloading. In the formation of shear-enhanced compaction bands, neither pore and crack nucleation nor pore collapse prevails due to their competitive interaction, resulting in multiple inclined or wavy bands, with continuous plastic development of porosity both inside and outside the bands. In the formation of pure compaction bands, discrete bands perpendicular to the maximum principal stress direction are formed, with hardening behavior induced by pore collapse dominating within the band.