A Bounding Surface Model for Cemented Soil at Small and Large Strains

Many constitutive models have been proposed to describe the mechanical behavior of cemented soil at large strains (above 1%). Less attention has been paid to the highly nonlinear stress-strain behavior at small strains, which are important for accurately analyzing the serviceability of many infrastructures. In this study, a bounding surface model was developed to simulate cemented soil behavior from small to large strains. Some new formulations were proposed to improve the modeling of small-strain behavior, including (1) the elastic shear modulus over a wide range of stress conditions, and (2) the nonlinear degradation of bonding strength (pb) with damage strain (ϵd) in the lnpb-ϵd plane. The new model was applied to simulate drained and undrained triaxial tests on cemented soils at different cement contents and confining pressures. Comparisons between the measured and computed results show that the new model can well capture many important aspects of cemented soil behavior, especially the elastic shear modulus at very small strains and stiffness degradation at small strains. Furthermore, the model gives a good simulation of strain softening/hardening and dilatancy/contraction during shearing under various confining pressure and void ratio conditions.