Elastic Dynamic Young’s Modulus and Poisson’s Ratio of Sand–Silt Mixtures

Abstract

The significant influence of silica nonplastic fines content on the small-strain Young’s modulus and Poisson’s ratio of silty sands has been evaluated through a comprehensive set of resonant column tests in the flexural mode of excitation. It is demonstrated that at low fines contents, sand properties have a significant impact on the dynamic behavior of the soil; however, the silt inclusion is the predominant feature controlling Young’s modulus beyond a specific proportion of fines content. Based on the flexural resonant column tests performed on the sand–silt mixture specimens with variable parent sand materials in terms of uniformity coefficient and particle shape, a new expression is established for the evaluation of the small-strain dynamic Young’s modulus of silty sands using the concept of equivalent granular void ratio. Having a typical micromechanical discussion, the influence of confining pressure, particle shape, and fines content on the small-strain stiffness of sand–silt mixtures are thoroughly described. Furthermore, invoking the theory of elasticity, the variation of Poisson’s ratio with fines content for sand–silt mixtures is discussed.