Micromechanics-based stress–strain behaviour of soils at small strains

A model that describes the small-strain behaviour of soils is derived using micromechanics theory. The model allows examination of the effects of fabric anisotropy, stress conditions and contact characteristics on the small-strain modulus of soils. The closed-form solutions of the small-strain modulus are presented for the case of an isotropic fabric assembly under isotropic stress conditions. A fabric tensor is used to model the fabric anisotropy, and the small-strain modulus for the case of cross-anisotropic fabric assembly under general stress conditions is numerically calculated. The effect of the contact condition between soil particles is examined by incorporating three different contact laws (the linear elastic, Hertz–Mindlin and rough-surface contact models) into the model. It was found that the numerical results using the rough-surface contact model compare well with the published experimental data, and that the model provides microscopic insight into the small-strain behaviour of soils observed in the laboratory.