Post-Construction Safety Assessment of a High Concrete Face Rockfill Dam

Abstract

The most important issue regarding the safety and performance of concrete face rockfill dams (CFRDs) is to determine stresses and deformations. However, predictions of crest settlements of concrete face rockfill dams (CFRDs) are usually performed by using empirical relationships. Since, in recent years, CFRDs are constructed much higher and more complicated topographical and geological dam sites, these require performing numerical analysis to evaluate the stress and deformations in the entire dam body. Numerical estimation of deformations and crest settlements is also crucial particularly to determine parapet wall heights and freeboard allowances at the design stage. In addition, assessing long-term rockfill behavior and the concrete face membrane crack potential are important for post construction dam safety. The objective of this study is to evaluate post-construction deformations and crest settlements of a high concrete faced rockfill dam under two different loading cases considering nonlinear elasto- plastic behavior of the rockfill structure. As constitutive model, Duncan-Chang hyperbolic stress-strain model was applied in finite element simulations considering the failure criterion is isotropic and hardening. Calibration of the rockfill's hyperbolic parameters was performed by comparing the calculated displacements with the actual settlement measurements from the instruments. Computed crest settlements were also compared with those of some CFRDs given in the literature. Calculated crest settlement and other deformations were in good agreement with the rockfill settlement measurements and in acceptable ranges, and do not threat the dam's safety.