A dynamic analysis procedure for concrete-faced rockfill dams subjected to strong seismic excitation

There is presently little analytical and essentially no observational evidence on the behavior of the concrete-face of the very popular concrete-faced rockfill (CFR) dams during strong seismic shaking. The choice of slab thickness and steel reinforcement is based solely on precedent, with performance under static loads being the only design consideration. To fill this gap, a dynamic finite element (FE) procedure is presented to design the concrete-face slab which involves a realistic modeling for the embankment material, the face slab, and the slab-rockfill interface. A set of historic accelerograms, with peak ground accelerations (pga) of about 0.66 g, is used as excitation. Numerical results highlight key aspects of the seismic response of CFR dams with emphasis on the internal forces developing in the slab. It is shown that slab distress may be produced only from axial tensile forces, developing mainly due to the rocking component of dam deformation. For the 0.60 g shaking tensile stresses much higher than the likely tensile strength of concrete development in the slab. All analyses in this FE study are performed with the ADINA special interface elements to model the slip and Newmark's time-integration algorithm for a direct step-by-step solution. (C) 1999 Elsevier Science Ltd. All rights reserved.