Rockfill Particle Breakage Generated by Wetting Deformation under the Complex Stress Path

Wetting deformation of the rockfill material, which is generated by particle sliding, breakage, and rearrangement, plays a vital role in earth-rockfill dam deformation that determines the safety of the dam. However, the previous wetting deformation particle breakage test was performed under the conventional stress path, which could not reflect the influence of stress path. This paper investigates the particle breakage of the basalt rockfill used in the Gushui dam during wetting deformation tests under the equal stress ratio path and drained triaxial shearing tests under the complex stress path. The results indicate that stress path, stress level, stress intensity, and particle breakage determine the wetting deformation under the equal stress ratio path. Under a low confining pressure (1,000 kPa), rockfill particle sliding and roll over are loosely constrained, and negligible particle breakage occurs during wetting deformation, which is mostly generated by particle sliding and rearrangement. Under a high confining pressure (2,000 kPa), rockfill particle sliding and roll over are more constrained. Thus, the contact force significantly increases and significant particle breakage occurs during wetting deformation. In addition, the relationship between the relative particle breakage index and plastic work under the equal stress ratio path and the following wetting deformation period can be simulated with a hyperbolic formulation, which cannot reasonably simulate the particle breakage under the transitional stress path after wetting deformation. The wetting deformation function under the equal stress ratio path was developed to incorporate the influence of the particle breakage and stress path.