Abstract：To investigate the micromechanical of shear properties of rubbersand mixtures, the direct shear test of rubbersand mixtures was numerically simulated by PFC3D discrete element program. The effects of vertical normal stress and rubber content on the macro and micro mechanical behaviors of rubbersand mixtures were analyzed. The results show that the shear strength characteristics of pure sand are significantly improved by adding rubber particles. The shear stressshear displacement curve of rubbersand mixtures shows strainhardening characteristic, and the shear strength is increased with the increasing of vertical normal stress. The addition of rubber particles leads to the increasing of coordination number, strong force chain number and total force chain number, which leads to the formation of more stable force chain system. When the vertical normal stress is 200 kPa, the coordination number, the strong force chain number and the total force chain number of rubber sand mixed with 15% rubber particles are respectively increased by 361%, 253% and 277% compared with those of pure sand. Compared with pure sand, the addition of rubber particles inhibits particle rotation, while that has slight effect on the normal contact force and tangential contact force between particles.
