Abstract: Establishing a constitutive model for granular materials that accounts for particle shape and breakage mechanisms has been crucial for calculating the mechanical stability of earth-rock dam projects. Initially, through the triaxial compression tests, the effects of particle breakage, rotation and sliding on the deformation of granular materials with varying shapes are examined. The particle slip/rotation is dominant at low stress level, and the energy dissipation is small. With the increase of the stress level, the influences of particle breakage are more prominent. Subsequently, the mathematical expressions for the particle crushing energy and dilatancy energy that consider particle shape are developed based on the geotechnical damage mechanics and thermodynamics. By incorporating the particle breakage rate equation, the evolution laws of particle crushing energy dilatancy energy, and breakage degree during compression are elucidated, quantitatively revealing the meso-particle breakage deformation mechanism. These mathematical relationships of meso-deformation mechanisms are integrated into the D-C model, then an elastoplastic constitutive model that considers both the particle shape and the meso-particle breakage mechanisms is derived. Finally, the validity and reliability of the proposed model are confirmed by comparing the experimental curves with the theoretical predictions.