Discrete element modeling of contact creep and aging in sand

In this study, aging in dry, clean sand induced by contact creep is investigated through numerical simulations using the discrete element method. Simulation results demonstrate that contact creep initiates the redistribution of contact forces. Although contact creep produces a very small decrease in porosity (approximately 1.7%), a significant change in the contact force distribution is produced in the aged sample. The contact forces ultimately become more uniform in both magnitude and spatial distribution. This homogenization of contact forces leads to more stable force chains and therefore produces an increase in the small-strain stiffness, early strength, and dilatancy in the aged sample. Such increases are not found in the sample prepared to the same porosity as the aged sample but without aging. This is because, in generating this sample, the contact creep is not allowed and therefore its associated contact force distribution is less homogenized compared with that in the aged sample.