Dilatancy Equation for Rockfill Materials under Three-Dimensional Stress Conditions

Abstract

The intermediate principal stress ratio b has a significant influence on the dilatancy behaviors of rockfill materials. The dilatancy equation is defined as a function of the dilatancy dg and the stress ratio η. To investigate the applicability of a dilatancy equation when considering the influence of the b-value, a series of true triaxial tests including constant b-value (CB) tests and plane strain tests were performed. The results of the CB tests indicated that the stress ratio at the critical state, Mc, remarkably decreases with increasing b-value. By comparing the results with three widely used interpolation functions, a newly proposed interpolation function was suggested to express the relationships between the material constants of the dilatancy equation, i.e., Mc, A, and C, and the Lode angle θ (b-value). Additionally, the predictions of the dilatancy equation considering b-value agreed well with the rearranged test data of the constant-b and plane strain rockfill specimens. As a result, the dilatancy equation and the proposed interpolation function are believed to well express the dilatancy behaviors of rockfill materials under three-dimensional stress conditions.