Evaluation of the Effects of Different Strain Paths on the Behavior of Sands Using Direct Simple Shear Tests

Many researchers have evaluated different parameters that can affect the mechanical behavior of sands. However, most of the conducted investigations considered drained and undrained stress-strain paths as the limiting boundaries of the behavior; recently applied studies have indicated that this assumption cannot be accurate for all situations. In this paper, by using expansive and contractive strain paths (in addition to the conventional constant volume path), partially drained responses of sands are simulated. Influences of different grain size distributions on the behavior of sands are studied by controlled coupling between volumetric to shear strain ratios. The results show that the asymptotic stress ratio (steady state stress ratio), phase transformation stress ratio, and instability stress ratio depend on the experienced strain paths and cannot be considered material constant (inherent) parameters. It is shown that coarse sands can be affected by the various strain paths more than finer sands, and loose sands are more sensitive against the partially drained strain paths compared to dense sands.