Development of a Cohesive Strengthening/Damage-Plasticity Model Based on DEM and Its Parameter Influence Analysis

Although there has been a large amount of research focusing on the development of geotechnical constitutive models based on discrete element method (DEM), few studies have specifically considered the behavior of plastic hardening behavior and shear shrinkage deformation at the particle scale. In this study, we propose a novel bonded particle model by incorporating the hardening responses and shear-shrinkage effect between bonds. The new contact constitutive is formulated within the existing theory of cohesive damage-plasticity model (CDPM) and corrects the main drawbacks of the original model formulation (e.g., yield criterion, detection of loading/unloading pattern, failure criteria). The reliability of the proposed model is then verified by reproducing the complex response of cemented materials under uniaxial tension and triaxial compression tests. On this basis, a series of parameter influence analysis tests are carried out, and the results show that the shrinkage stress coefficient significantly affects the plastic deformation response of the sample during loading, the plastic hardening and softening parameters control the pre- and post-peak change rates of the stress–strain curve, respectively. While the peak and failure response of the curve are related to the strengthening and damage thresholds, respectively. Furthermore, by studying the evolution law of bond states, the microscopic mechanism behind the above macroscopic phenomena is further expounded.