Abstract: In order to study the deformation failure mechanism of soil-rock mixture under uniaxial compression in the presence of different rock block proportions,on the basis of the refined method for constructing discret element method(DEM) model of irregularly shaped particles, a random technique to constructing DEM model of irregularly shaped rock block is proposed and 3-D particle flow models of soil-rock mixture which conform to the macroscopic statistical rule are established. Then, particle flow simulations of uniaxial compression tests are conducted. It is noteworthy that with the increment of rock block proportions, the uniaxial compressive strength and the elastic modulus both decrease. Stress-strain curves of soil-rock mixture with medium-low rock block proportions (0, 10%, 30%, 50%) show a typical feature of strain softening; whereas stress-strain curves of soil-rock mixture with high rock block proportions (70%, 90%) show some degree of plastic flow characteristics after peak stress. Micro-cracks in the specimens of SRM with medium-low rock block proportions are mainly tensile cracks, resulting in macroscopic tensile rupture; while few micro-cracks develop in the specimens of soil-rock mixture with high rock block proportions, which are mainly shear cracks, resulting in macroscopic shear failure.

Key words: soil-rock mixture, irregularly shaped particles, 3-D particle flow, uniaxial compression test, DEM model