Deformation behavior of sands under cyclic non-proportional loadings

Drained tests for non-proportional loadings involving with cyclic variations of the deviatoric stress and principal stress axes were conducted on sands with a hollow cylinder apparatus at Hong Kong University of Science and Technology. The test condition was controlled to be that principal stress axes rotated cyclically from 0° to 180° to the vertical axis accompanied by the variation of the deviatoric stress simultaneously. The developments of three normal strain components and the volumetric strain with the number of cycles and the relationship between the shear stress and the shear strain components were analyzed in detail. With the increase of the cycle number, the contractive volumetric strain of sands induced is increasing, yet its increase rate is lowered. And it is found that the magnitude variation of the deviatoric stress plays a significant role in the deformation behavior of sands under cyclic non-proportional loadings.