Abstract: In order to reasonably reflect the influence of particle breakage on the mechanical properties of the rockfill material, it is obtained by the analysis of the test results that the particle breakage characteristics of the rockfill material under the compression and shear. By introducing the related parameters in the compression breakage and shear breakage, some reasonable definitions of the existing constitutive models are used. Taking the advantages on the critical state theory and the boundary surface theory, a unified constitutive model is developed considering the particle breakage and state parameter, and the determination method of model parameters is described. The model can reflect not only the low pressure dilatancy, high pressure shear shrinkage, strain softening and hardening phenomenon of the rockfill material under the static loading, but also the stress-strain hysteresis characteristics and the cumulative effect of residual deformation under the cyclic loading. Finally, in order to verify the reasonability of the model, the static triaxial and cyclic triaxial tests of rockfill material are carried out. The results show that the model prediction is in good agreement with the experimental data, and the constitutive model can reasonably describe the impact of particle breakage on the static and dynamic deformation characteristics of the rockfill material.

Key words: rockfill material, particle breakage, state parameter, critical state, constitutive model