Simulation of viscous effects on the stress-strain behaviour of a dense silty sand

The viscous aspect of the stress-strain behaviour of a compacted silty sand obtained from a special undrained triaxial compression test is analyzed. During otherwise strain-controlled monotonic loading, the strain rate was changed stepwise many times by about two orders of magnitude and several undrained creep tests were performed. The viscous response of specimen to such loading history depends on the geomaterial type. With this silty sand, at low strain levels, the stress is rather a unique function of instantaneous irreversible strain and its rate, while at larger strains, the viscous effect decays with strain, which is at a higher rate at larger strains. It is shown that among several three-component rheology models, the so-called general TESRA model is most relevant to simulate the observed stress-strain behaviour of the studied silty sand. The influence of the parameters controlling the model behaviour is analyzed.