Macro- and micro-properties and formation mechanisms of granular piles

A DEM study is carried out to simulate the construction of granular piles by considering various particle shapes. The underlying mechanisms are analyzed through the examination of the macro and micro-characteristics of granular piles. It is found that angle of repose decreases as particle shape evolves towards a regular pattern. Microscopically, the anisotropy magnitudes of contact orientation vectors, contact normal and tangential force vectors decrease as particle shape evolves from an irregular one to a regular one. The summation of the angle difference Δ?_n between the principal anisotropy direction of contact orientation vectors and the vertical direction, with the angle of repose α, is almost a constant, and the angel differences Δ?_f and Δ?_t for the principal anisotropy directions of contact normal and tangential forces are revealed to be a linear function of angle of repose α. In addition, a relationship is also established between the direction where the most intense arching effect occurs and the principal anisotropy directions of contact orientation vectors, contact normal and tangential force vectors.