Dilatancy equation of rockfill material under the true triaxial stress condition

Rockfill material is widely used for construction of high rockfill dam due to its facility, economical cost, high strength and effective aseismatic property. It is provoked profoundly to propose a suitable constitutive model for a better application of this material. The dilatancy equation of rockfill material plays a significant role in the constitutive model. For the sake of simplicity, a dilatancy equation is established by the linear least square method on the basis of the rearranged data of rockfill material in the true triaxial tests. Based on the fact that the rearranged data at different initial confining pressures are aligned in a narrow band, the dilatancy behavior of rockfill material is independent of the initial confining pressure. However, different from the initial confining pressure, both the intermediate principal stress ratio and the specimen density exhibit a remarkable influence on the dilatancy behaviors of rockfill material. Furthermore, the predictions of the proposed dilatancy equation are in a good agreement with the rearranged test data of rockfill material at different specimen densities and stress paths.