Effect of particle shape on the formation of sandpile

Abstract

This paper describes a DEM investigation of the formation of sandpiles and the angle of repose by focusing on the effect of particle shape. Special efforts are made to quantitatively analyze the particle arrangements and interactions, which are essential to the explanation of angle of repose from a micromechanical perspective. The DEM simulation results show that the angle of repose decreases with the increase of the shape parameter (aspect ratio and circularity). The intensities of fabric anisotropy described by particle and contact orientations both exhibit a negative correlation with the shape parameter. The principal anisotropy directions of contact orientations for the left and right parts of sandpiles deviate increasingly away from the vertical direction as the shape parameter is increased. A characteristic aspect ratio AR = 0.6 has been identified for the fabric anisotropy of particle orientations, at which the principal anisotropy directions for the left and right parts of sandpiles reach a compromise state and lie in the horizontal direction. Furthermore, the repose angle is found to be closely linked with the fabric anisotropy, with the sum of the repose angle α and deviation angle Δϕn (the angle formed between principal anisotropy direction of contact orientations and the vertical direction) being approximately a constant, regardless of the effect of particle shape. The arching effect in the sandpile is also examined through a statistical analysis of the distribution of forces at the bottom, and the mechanism underlying the formation of sandpiles is thus clarified.