Experimental Study on the Dilatancy Characteristics and Equation of Saturated Sand–Gravel Composites during the Whole Shearing Process

Abstract

The dilatancy equation plays an important role in establishing the elastoplastic model for sand–gravel composites. However, the equation is not comprehensive in its considerations. In this paper, experimental investigations of the dilatancy behaviors of saturated sand–gravel composites are carried out through a series of drained triaxial compression tests. The influence of density as well as confining pressure on the dilatancy characteristics of sand–gravel composites is analyzed, and a nonlinear relationship between the stress ratio η and the dilatancy d is suggested. A new and practical dilatancy equation that can accurately model the stress–dilatancy relationship of sand–gravel composites during the whole process of shearing is established. The equation is applicable whether the material is strain softening or strain hardening. The improved accuracy of the proposed equation in describing the stress–dilatancy relationship of sand–gravel composites is highlighted through comparison to the predictions of five widely used dilatancy equations. In addition, the generality of the proposed dilatancy equation is verified through analyzing the stress–dilatancy relations of six rockfill and gravelly materials found in published literature.