Numerical simulation of post-construction deformation of a concrete face rockfill dam

In this paper a novel hypoplastic constitutive model is used to investigate post-construction deformations of a concrete face rockfill dam caused by water impounding and creep. Creep deformations are related to the time dependent process of degradation of the solid hardness of the weathered rockfill material, in which the solid hardness and its rate is introduced into the constitutive model in the sense of a continuum description. The hypoplastic model captures the influence of pressure, density and state of the solid hardness on the incremental stiffness, the peak friction angle and the volume strain behaviour as well as the influence of a degradation of the solid hardness on creep and stress relaxation in a unified manner. The material parameters considered in the present study are relevant for weathered broken granite. The results obtained from the finite element simulations are compared with monitoring data of four different concrete face rockfill dams. It is demonstrated that the solid hardness and its degradation velocity are key parameters for modelling long-term deformations. For the constitutive parameters assumed long-term deformations after 15 years are more pronounced than the instantaneous deformation caused by the first water impounding.