Abstract:  In order to obtain the shear properties of the fault material, five irregular particle units generated by the discrete element method were used to simulate the direct shear process of the fault under natural conditions. By using the experimental data as the simulation parameters, the influences of shear stress of fault were studied with different normal stress, the friction coefficient, particle shape and composition of the irregular particles. The results show that the shear stress increases as the increasing of normal stress, the friction coefficient and the amount of the irregular particles. Furthermore, the changes of porosity under different normal stress, particle shapes or compositions show the changes of shear stress.

Key words: direct shear test, discrete element method, granular matter, fault material