How fines content affects granular plasticity of under-filled binary mixtures

Abstract

In recent years, binary mixtures have been the subject of numerous experimental and numerical studies. However, few attempts have been made on investigating the effect of fines content (fc) on the non-associated plasticity of binary mixtures, which is significant for constitutive modelling of such material. Thanks to 2D DEM simulations, this study aims to provide an understanding of how fc affects the non-associated character of the flow rule and the resulting material instability in binary mixtures. For under-filled materials (where coarse grains constitute most of the load-bearing skeleton), fine grains help to stabilize the granular assembly (1) by limiting macroscopic plastic deformations, which results in strain hardening, and (2) by reducing contractive microstructure reorganizations, which reduces the gap between the associated and non-associated flow rule directions. Fines content influences the plastic flow direction but has no influence on normal direction of yield surface. Eventually, perspectives on mesoscale mechanisms are given to highlight the role of fine grains in the geometrical and mechanical properties of granular materials.