MONOTONIC BEHAVIOUR OF SAND UNDER TORSIONAL LOADING WITH DIFFERENT CONFINE STRESS

This study assessed the effects of anisotropy in sands with various confining stresses. The tests conducted in this research include 20 hollow cylinder torsion shear tests under torsional loading conducted on Tehran sand with high angularity. The confining stresses of the samples were 100, 200 and 400 kPa, and the effect of the inclination angle of the major principal stress to the vertical axes was also studied. In each confine stress three inclination angle 15, 30 and 60 degrees were applied. According to the results, an increase in the alpha will result in a more contractive behavior in the sands. The effect of anisotropy also becomes more obvious, as the confining stresses increases; however, it was found that the mechanical properties of sands changed markedly with confining stress. To explain the effect of particle shape on the mechanical behavior of sand, with its increase the soil sample behaved in an isotropic manner and the shear strength of the sample decreases.