Effects of Grain Shape on Mechanical Behavior of Granular Materials Using DEM Analysis

To examine the effect of the grain shape on the mechanical behavior of granular materials, a series of the three dimensional distinct element method (DEM) simulations of the true triaxial test were carried out under plane strain condition. Six kinds of clump elements with a different microscopic angularity using two or four spherical elements were generated base on a coefficient of form unevenness (FU) as a shape factor. The maximum mobilized internal friction angle, the formation of the shear band, and the structural anisotropy based on the principal fabric tensor were examined with the FU value. As a result, it is found that the relationship between the maximum mobilized internal friction angle, φ_max and the FU value corresponds linearly. As the grain shape became more spherical with the increase of the FU value, the shear band appeared less clearly. It was also found that because the specimen with the larger FU value caused more structural anisotropy, the structural anisotropy depends on the FU value. Thus, it can be said that the FU as the shape factor can be a practical criterion to evaluate the effect of the grain shape on the mechanical behavior of granular materials.