PARTICLE SHAPE AND CRUSHING EFFECTS ON DIRECT SHEAR BEHAVIOR USING DEM

Abstract

Numerical analyses using the PFC(2D) are conducted to study the relative changes of particle crushing and the shear behavior of granular materials according to the quantified particle shapes. A total of seven particle shapes are standardized and quantified. Three different particle models, including a circular particle model, a non-crushing particle model, and a crushing particle model, are developed and analyzed. The results show that shear strength is mobilized in size order: 3 ball > 6 ball_T > 2 ball > 6 ball_R > 4 ball > 9 ball > 1 ball model, corresponding to triangle > rectangle > square > circle shape in both the non-crushing particle model and the crushing particle model. Within the same shape but with a different number of sub-particles, it is found that an increase in the number of sub-particles within a particle coincides with smaller shear strength per model. The non-crushing particle model shows the increase of porosity not only in the shear band, but also in other layers. However, in the case of the crushing particle model, the increase of porosity is mainly focused within the shear band. It is found that with a larger circularity and convexity, that is, as a particle becomes more circular in shape, the shear strength decreases, regardless of particle crushing. It can be concluded that the standardized particle shape model suggested in this research has broader applications for future studies.