Discrete Element Method Simulation of Dynamic Behavior of Granular Materials

Granular soils have complex macroscopic response under seismic loading. Due to the many uses of the results of cyclic triaxial tests, the numerical modeling of these tests is needed to facilitate the prediction of soil behavior and reducing the cost of laboratory tests. The aim of the present research is to evaluate the ability of the discrete element method to investigate the dynamic behavior of sand by simulating a number of drained stress controlled cyclic triaxial tests under three-dimensional conditions. In addition, the effect of parameters such as number of loading cycles, soil relative density, cyclic stress ratio, particle shape and loading paths on the dynamic properties of soil (shear modulus and damping ratio) is also considered. The results indicate that numerical simulation by discrete element method can accurately represent the variations of soil dynamic properties with the considered variables. The comparison of experimental results from the literature and numerical models carried out in this study shows that the rate of decreasing in shear modulus and increasing in damping ratio of the samples with non-spherical particles with shear strain is higher in the given cyclic stress ratio and porosity. The cyclic stress ratio does not have significant effect on the shear modulus, damping ratio and coordinate number of samples. The coordinate number of the sample with spherical and non-spherical particles (e=0.3) is obtained 7.7 and 6.4, respectively, at the end of the simulation test. In the same condition, the samples with non - spherical particles have undergone more deformations.