Particle breakage of rockfill during triaxial tests

The particle breakage directly modifies the structure of the rockfill, influencing its dilatancy, friction angle, strength, permeability and creep deformation. However, the breakage law of the rockfill during shearing is still unclear. The particle breakage of the basalt rockfill of Gushui concrete face rockfill dam during the sample preparation, consolidation and drained triaxial shearing is studied by using the consolidated-drained triaxial tests. The research shows that the sample preparation of the rockfill generates notable particle breakage. The isotropic consolidation of the sample generates little particle breakage. Under low confining pressure, the particles can freely roll over and slide, and there is little particle breakage during the shearing. Under high confining pressure, the rolling and sliding of the particles are limited, which increases the interlocked force among the particles. And the particle breakage increases with shear strain. During the particle breakage, the large particles break first. The diameter of the broken particle decreases with the increasing confining pressure. The content of the particle less than 0.5 mm always increases with the increasing pressure and the amplification also increases with the increasing confining pressure. Under high confining pressure, the stress and shear strain both influence particle breakage. The relationship between the relative breakage parameter Br and the shear strain under the same confining pressure can be described by hyperbolic formula.