Behavior of Concrete-Faced Rockfill Dams during Initial Impoundment

Centrifuge tests to investigate the behavior during initial reservoir filling of a concrete faced rockfill dam (CFRD) with face slab stiffnesses that vary by a factor of about two are described. The two centrifuge models exhibited similar deformations at the crest and along the face slab, with crest settlements averaging 0.19H (%) and maximum face slab deformations averaging 0.88H (%). The centrifuge test results suggest that the face slab stiffness had little effect on deformations, at least for the range of stiffnesses examined here. A parametric study of transition (supporting) zone stiffness was performed using a numerical model calibrated using the centrifuge results. The numerical results indicated that face slab deformation is more influenced by transition zone stiffness than face slab stiffness, supporting the centrifuge results. Deformation measurements for 25 in-service CFRDs (including six Korean CFRDs—one of which was used as the basis for the centrifuge model dam) are presented and compared with the experimental and numerical results. The centrifuge experiments exhibited crest settlements similar to the Korean CFRDs; however, the centrifuge models exhibited considerably larger maximum face slab deflections. The larger values measured in the centrifuge tests likely resulted from some experimental limitations. These limitations, as well as suggestions for improving future centrifuge studies of CFRDs, are discussed.