Time-Dependent Mechanical Behavior of a Granular Medium Used in Laboratory Investigations

The time-dependent mechanical response of an artificial granular medium consisting of glass beads is experimentally examined by performing one-dimensional creep tests on both saturated and dry specimens. The time-dependent compression of the oedometric sample, which is related to the internal rearrangement of the granular assembly, is modeled using an elastic-viscoplastic strain hardening constitutive model. The procedures used to identify the parameters defining the model are discussed; the incremental strain of the material is decomposed into reversible elastic and irreversible creep components. Finally, the capabilities of the proposed model in predicting the time-dependent response of the material are investigated through a comparison between experimental results and analogous results derived from computational modeling.