Micromechanical modelling of the anisotropic viscoelasticity of granular materials: statistical homogenization

Granular materials can exhibit a viscoelastic behaviour resulting from a) the viscoelastic character of the material the grains are made of, b) the presence of a viscous or viscoelastic fluid between particles. The micromechanical modelling of the behaviour of such materials considering a statistical homogenization approach is performed in this paper. Several homogenization schemes are first reviewed. The main differences between these schemes lie in the way statistical distributions of local variables are related to the global variables. Once the viscoelastic contact law is chosen (based on physical considerations), the overall behaviour can be derived. The later is shown to be dependent on the wave velocity. Furthermore, an anisotropic behaviour is obtained if a description of the interparticle contact distribution is included. The respective influence of wave velocity and contact distribution anisotropy is determined. The relevance of this approach is shown in the last section of this paper through a comparison with experimental results on bituminous concrete.