A comprehensive numerical investigation of multi-scale particle shape effects on small strain stiffness of sands

The effects of multi-scale particle shape characteristics on small strain stiffness of granular soils remain controversial. This study revisits this topic using well calibrated three-dimensional discrete element simulations incorporating into particle roughness-embedded contact model and realistic shape particles. Based on the numerical simulation results, the multi-scale particle shape effects on the small strain stiffness of sands and magnitude of Hardin's equation parameters are systematically investigated, and the underlying micro-mechanisms are also thoroughly explored. Results indicate that the small strain stiffness increases with the increase of particle overall irregularity due to the increased mechanical coordination number, while decreases with the increase of particle surface roughness because of the decreased contact normal stiffness. And the constant term and void ratio term parameters of Hardin's equation increases and decreases linearly, respectively, with the particle overall regularity, while reduces and grows with the particle surface roughness, respectively. Furthermore, the stress exponent is almost unchanged with the particle overall regularity, while increases with the particle surface roughness which determines the relative proportions of contacts under asperity dominated, transitional and Hertzian stages. The study helps to advance our cross-scale understanding of multi-scale particle shape information in relation to small strain stiffness of sands.