Abstract: Dilatancy, representing the plastic flow direction of granular material, is an important part in elastic-plastic constitutive model. So far, the dilatancy equation of rockfill is mainly obtained by the conventional triaxial test, and it is not clear whether these dilatancy equations can reflect the dilatancy law of rockfill under different stress paths. In this paper, tests with four different stress paths, including constant confining pressure , constant axial stress , constant mean effective stress p, and constant principal stress ratio are conducted to study the influence of stress paths on the dilatancy. The results show that: the dilatancy ratio is linearly associated with the stress ratio under different paths, but there is no consistent relationship between the dilatancy ratio and the stress ratio; the dilatancy line translates and rotates with the stress increment direction in the - space, and the slope parameter and the intercept parameter are increased with the increase of ; the existing dilatancy equations cannot well describe the dilatancy relationship under different stress paths, and a modified dilatancy equation considering the stress increment direction is proposed and verified.

Key words: stress paths, dilatancy, rockfill material, stress increment direction, elastic-plasticity