Impact of Gradation Effects on the Particle Breakage and Mechanical Response of Calcareous Sands

Calcareous sand is distinguished by its angular particle shape and high susceptibility to breakage during shearing. The particle size distribution (gradation), interparticle density, and particle strength play pivotal roles in determining its deformation and strength properties. This study proposes a novel gradation equation to predict particle breakage and the shear behavior of calcareous sand with varying particle size distributions. A total of 108 triaxial tests were performed to validate the proposed model. The results indicate that broader particle size distributions exhibit higher energy absorption efficiency within the same gradation group. At a constant relative compactness (Dr), cohesion initially decreases with an increase in the gradation parameter β, reaching a minimum value of 15 kPa around β = 2.1 when Dr = 50% before increasing again. Additionally, a prediction model was developed to quantify shear strength and the breakage index for different gradations of calcareous sand. The findings of this study provide a predictive method for estimating the shear behavior and particle breakage of calcareous sand with diverse gradation.