Abstract: In numerical simulation of geotechnical engineering, it is a priority to correctly select parameters, which reflects the real mechanical behavior of materials. Within the scope of particle flow code(PFC2D) as the particle discrete element method theory, a number of plane biaxial compression simulation tests are carried out for cohesive materials in the present study. According to peak axial stresses recorded under different confining pressures, internal friction angles and cohesions of specimens are defined following the Mohr-Coulomb strength criterion. After analysis of the simulation data, the relationship is interpreted between particle mesoscopic parameters of cohesive materials, including particle stiffness ratio of 0.5 to 10, particle bond strength of 0 to 50 kPa, particle friction coefficient from 0 to 6, particle bond strength ratio of 0.1 to 10, and material macroscopic shear strength parameters. The result shows that particle friction coefficient is logarithmically related to the internal friction angle of material; and particle bond strength is linearly related to the cohesion of materials. It is also noted that particles stiffness ratio and particle bond strength ratio have slight influences on material mechanical parameters; and the particle bond strength ratio significantly affects the shear failure form of the materials. Two final formulas are then established for the quantitative combined relationship between particle mesoscopic parameters and macroscopic shear strength parameters of cohesive materials after multiple nonlinear fitting. In these formulas, the proposal value of particle bond strength ratio is given for the mechanism of cohesive materials.

Key words: discrete elements, particle flow code, mesoscopic parameters, biaxial compression test