Investigation of Creep Behavior and Its Effect on Dilatancy of Rockfill Materials through Large-Scale Triaxial Testing

A series of triaxial creep tests were carried out on the rockfill material to investigate its creep behavior. The variations in the creep strain and particle breakage of the rockfill material were analyzed, as well as their correlations. Meanwhile, the effect of creep behavior on dilatancy and the difference between creep and plastic dilatancy were also analyzed. The creep strain increased nonlinearly with time, and the final creep strain also increased as the stress level and the confining pressure increased. The change in the grading of the rockfill material was remarkable upon shearing and over creeping, indicating the occurrence of particle crushing. Furthermore, the relative breakage over creeping was significantly influenced by the stress level and confining pressure, and the creep strain was closely related to the relative breakage. The rockfill material exhibited volumetric contraction over creeping, resulting in increasing dilatancy over creeping compared to shearing. The formulas were proposed to represent the variations in the creep strain, particle breakage, and dilatancy of the rockfill material through nonlinear regression of the test data.