A coupled damage-plasticity DEM bond contact model for highly porous rocks

In view of the significant stress loss induced by stuructural collapse when simulating high-porous soft rocks using traditional damage bond models in DEM (discrete element methd) modelling, a novel damage bond contact model is proposed to capture the ductile failure of high-porous cemented soft rocks. To address the unrealistic physical contact distribution resulting from the use of spherical particles in DEM modelling and consider the physical presence of broken bonds, far-field interaction is introduced between grains when two untouched particles reach a specific activation gap, enabling the genration of stable, highly porous open structure samples while using spherical DEM particles. The final results demonstrate that this newly developed model facilitates the transition from the purely elastic rock-like behaviour stage to the transitional ductile failure stage of porous soft rocks, as well as reproduces the softening/hardening response of soft rocks under different confinements.