Particle Breakage of Rockfill Material during Triaxial Tests under Complex Stress Paths

Particle breakage modifies the structure of rockfill material and influences its constitutive character, which is the key factor in earth-rockfill dam deformation control. However, the particle breakage laws for rockfill material under real stress paths during dam construction and impounding remain unclear. This paper investigates the particle breakage of basalt rockfill, which was used in the Gushui concrete-face rockfill dam, during drained triaxial compression under equal stress ratio paths (construction stress paths) and transitional stress paths (impounding stress paths). The results indicate that the type of stress path significantly influences rockfill particle breakage. Under the equal stress ratio path, particle breakage increases with shear strain and the growth rate decreases with the stress ratio. The relationship between the relative particle breakage index and the plastic work can be simulated using a hyperbolic formulation. Under the transitional stress path, particle breakage also increases with shear strain and the growth rate is influenced by the transitional confining pressure, the transitional stress path, and the equal stress ratio experienced before the transition. However, the relative particle breakage index cannot be reasonably simulated using the plastic work.