Long-term response of granular materials subjected to repetitive mechanical loads: Engineering implications

This study investigates the long-term response of granular materials subjected to repetitive mechanical loads through integrated experimental and numerical approaches. Repetitive Ko-loading tests, triaxial tests, and simple shear tests reveal two critical asymptotic states governing system behavior: (1) a terminal void ratio controlling volumetric stabilization, and (2) stressobliquity- dependent shear modes transitioning between shakedown and ratcheting. Results demonstrate that repetitive loading alters the coefficient of earth pressure through fabric evolution, quantified via shear wave velocity-stress relationships. Granular degradation analyses show particle abrasion dominates at low-stress/high-cycle conditions, while fines content critically influences deformation response through threshold fines fractions. A new dimensionless shear stress ratio successfully predicts long-term shear response between shakedown and ratcheting. Hybrid numerical modeling combining conventional constitutive model with empirical strain accumulation reduces computational errors and enhance convergency to conventional methods for high-cycle simulations.