Impact of void ratio and state parameters on the small strain shear modulus of unsaturated soils

Abstract

The unsaturated small strain shear modulus, Gmax, is a key reference value in predicting relationships between dynamic shear modulus and shear strain amplitude and is thus a key quantity to properly model the behavior of dynamically-loaded geotechnical systems such as pavements, rail beds, and machine foundations. From the interpretation of the experimental Gmax results for unsaturated soils, different definitions of trends between Gmax and the stress state of the unsaturated soils and material properties are proposed. However, in most of trends, the relationship between the stress state and void ratio is considered and the effect of void ratio on the unsaturated small strain shear modulus is not fully investigated. In the study presented herein, Gmax data published in the technical literature for two different types of unsaturated soils are critically reviewed with the goal of identifying trends with path-dependent stress state and void ratio. The literature data is also used to evaluate the reliability of an existing approach in predicting the small strains shear modulus of unsaturated soils under different loading conditions.