Numerical simulation of biaxial test for granular materials based on discrete element method

In order to obtain the relationships between the mechanics parameters of granular materials and test conditions, discrete element method(DEM)was applied to prepare the initial specimens and simulate the biaxial test of granular materials with five particle diameters.The influences of different confining pressures on the elastic moduli, the strengths and the variation rules of elastic moduli, the Poisson's ratios and the strengths under different loading velocities were analyzed.The stress-strain curves of five specimens were plotted under confining pressure of 10 MPa and loading velocity of 0.03 m·s^-1, and the crack distributions in the specimens were also given from microscopic viewpoint.Simulated result indicates that the elastic moduli and strengths of five specimens increase with confining pressures, and the increasing trends are relatively smooth.However, the specimen with 9.50~13.20 mm particles has a bigger fluctuation.The relationships between loading velocity and the elastic modulus, the Poisson's ratio, the strength and the crack-initiation stress are quadratic polynomials basically, the minimum correlation coefficient is 0.900 9, and the maximum correlation coefficient is 0.995 9.In addition, the peak values of stresses obtained from stress-strain curves reduce with the increase of particle diameters.