Discrete element modeling of particles sphericity effect on sand direct shear performance

Particle surface morphology is an important factor influencing sand structure and mechanical properties. In this study, the effect of sand particle sphericity on sand direct shear performance is investigated by using the discrete element method (DEM). Two ways are adapted to simulate different approaching methods from round particles to irregular sand. The macroresponse shows that irregular sand has a higher shear strength at lower normal stress than round particles. The shape of the particle has less influence on shear strength at higher normal stress. The irregular shape of sand leads to an increase in the shear band proportion. However, the shear band proportion is not related to the sphericity. Under all conditions, particles within the shear band have a larger average rotation angle than those outside the shear band. When the particle shape approaches round (regardless of the round particle proportion and particle shape), the average rotation angle of particles within and without shear bands increase, while the coordinate number and contact anisotropy decrease.