Abstract
Geometrically, axi-symmetric systems are frequently encountered in soil mechanics and geotechnical engineering. This paper proposes a mixed boundary environment for such axi-symmetrical discrete element analyses. In the proposed approach, only one quarter of the system is considered. Two vertical (circumferential) periodic boundaries are used to enforce the conditions for axi-symmetry in the model. The proposed algorithm was implemented in a three-dimensional discrete element code to model axi-symmetric triaxial tests. To facilitate these triaxial test simulations, a cylindrical stress controlled membrane was developed. Simulations of triaxial compression tests on specimens of spheres with regular packing configurations are used to validate the proposed analysis approach.