Abstract: Granular materials are widely used in rockfill dams, subgrades and other projects; particle shape is an important factor affecting their mechanical properties, which is worthy of further study. In this work, a combined finite and discrete element method (FDEM) is used to simulate the triaxial tests of aggregates of ellipsoidal particles. To investigate the force transfer characteristics of granular materials, nodal forces in the contact area of particles are aggregated using the density-based spatial clustering of applications with noise (DBSCAN). We identify the information of particle contact and examine the effects of different particle shapes on the macroscopic and microscopic mechanical properties. Results show that in terms of macroscopic response to a shift in particle shape away from the sphere, the deviatoric stress of the global granular system increases obviously, accompanied by stronger dilatancy. In terms of microscopic response, shape change significantly increases the number of contacts in a granular system. And remarkably, the proportions of the super strong and very weak contact forces both are increased, and heterogeneity in the distribution of contact force magnitude increased. The results also reveal a significant increase in fabric anisotropy, and the increases in the anisotropy of contact normal vectors and branch vectors are most significant.

Key words: rockfill materials, particle shape, DBSCAN, force transfer characteristics, anisotropy