The effects of changing the deviatoric and spherical stresses during cyclic loading on the drained response of a sand

Changing the deviatoric and spherical stresses could affect the accumulative deformation behaviour of soils under cyclic loading. Drained cyclic triaxial loading tests were performed on saturated sand to study the dependence of cyclic loadinginduced axial and volumetric strain accumulations on changing the deviatoric and spherical stresses in between loading cycles. The change in the stresses was simulated by changing cell pressure and axial load along different stress paths. The variation of axial and volumetric strain accumulations before and after changing the stresses is compared and discussed. It is found that changing the stresses could have different impacts on the axial and volumetric strain accumulations, as the accumulations are affected by different mechanisms. The axial strain accumulation after changing the stresses is affected by the average stress ratio and precedent stress history. The volumetric strain accumulation is hardly affected by changing the stresses unless an increase in the average stress ratio is caused. Both axial and volumetric strain accumulations show independence on the stress path of the disturbance. For the samples with decreasing average stress ratio, the strain accumulation direction after changing the stresses cannot be fully described using Modified Cam Clay flow rule.