Combined effects of particle shape and strain rate on the ring shear response of granular soil

This study aims to visualize the combined effect of shape and strain rate on the mechanical response of monodisperse granular materials through 3D DEM ring shear tests. One part of the simulations implements contact-scale rolling resistance friction (RR friction) parameters to mimic particle angularity, and the other part takes idealized spherical particles, and further subjecting both to varying normal stress and shear strain-rates. Considering both simulation schemes, lower strain-rate accentuates material stiffness along with increased contraction of the specimen. Conversely, higher strain-rate promotes delayed contraction along with higher deviatoric strength and reduced stiffness. Specimen having particle scale rolling friction gives higher peak and residual strength along with shift in critical state regime compared to idealized spherical specimens. Further, ensemble-scale porosity and co-ordination number has been investigated to provide a micro-scale perspective on the responses.