Rockfill dams present a challenge for engineers due to the many uncertainties revolving around the behavior of these geotechnical structures. A governing factor in the behavior of rockfill is the particle breakage due to change of moisture, as observed in laboratory and field conditions. Many constitutive models exist for soils but rockfill remains yet a relatively unexplored area and deserves more attention. The particle breakage phenomenon has been incorporated in a rockfill compressibility constitutive model by Alonso and Oldecop, where the suction inside the cracks of the rockfill is a state variable that controls this mechanism. A numerical study on a well instrumented rockfill dam is conducted using this constitutive model. The dam consists of rockfill shoulders and a central clay core, and has experienced considerable collapse settlement due to impoundment and rainfall. The instrumentation data provide an excellent opportunity to examine the state-of-the-art modeling techniques for settlement response of rockfill dams. The simulation of the stage construction and impoundment phase is carried out using the above model in Code_Bright, which is a fully coupled three-phase finite element program for unsaturated porous media. Simulation results are used to examine a recently proposed scaling law by Oldecop and Alonso for the compressibility of rockfill. The study concludes with comments on the accuracy of the scaling law and ideas for future developments.
