DEM modelling of highly porous soft rocks

A novel bond damage model is proposed to better replicate the behaviour of highly porous soft-rocks. The contact model employs an exponential damage law to describe the permanent deformation developing at the microscale. To i) reach a high porosity initial state, ii) reproduce complex contact configuration of irregular grains and iii) consider the physical existence of fractured bond fragments, a far-field interaction is introduced in this model, enabling non overlapping particles to transmit forces. The model performance is validated by replicating the behaviour of Maastricht calcarenite. Finally, a 3D coupled DEM (Discrete Element Method) - FDM (Finite Difference Method) modelling is employed to simulate the penetration of a cone-end shaped pile in calcarenite. The good agreement between the experimental and numerical results suggests that the proposed model has the potential to reveal microscopic mechanism of soft-rock / structure interaction.