Deformability of polydisperse granular materials: the effect of size span and shape of grain size distribution

Abstract

This paper investigates the effect of the grain size distribution (GSD) on deformability of spherical particle assemblies using the distinct element method. The GSD is modeled by a normalized beta function, which allows variation of the size span (nearly monodisperse to highly polydisperse) and the shape (approximately linear to strongly curved) of GSD. A series of triaxial compression tests is simulated on a set of assemblies with varying GSDs under different packing fractions and confining pressures. The compressibility under isotropic loading and deformation modulus during shearing are examined for various GSDs. The results show that the size span and shape of GSDs affect the packing conditions of the assemblies but have negligible influence on the compressibility and deformation modulus of the assemblies under the same packing conditions. A unique correlation is found between the deformation modulus and the mechanical coordination number, which can be estimated from the effective void ratio.