Effects of particle characteristics on small-strain dynamic properties of granular materials

The small-strain shear modulus and damping ratio are the important dynamic properties of granular soils. Controversial views exist regarding the effects of particle shape and size on the small-strain dynamic properties. In this study, the small-strain shear modulus and damping ratio are measured systematically for the specimens formed by polycarbonate particles with well-controlled particle shape and size using the energy injecting virtual mass resonant column system. The test results show that the particle size has few effects on the small-strain shear modulus and damping ratio, while the particle shape has significant impacts. The shear modulus of the specimens of spherical particles is smaller than that of the elliptical particles and the clumped particles under otherwise similar conditions, while the damping ratio of the specimens of spherical particles is higher than that of the specimens of the other two particles. For the mixtures of spherical and elliptical particles, the small-strain shear modulus and damping ratio are between those of the specimens of each type of particles. The overall regularity, quantifying the shape of the particles, can be used to characterize the small-strain properties of the specimens.