| Sliding stability of concrete gravity dams must be considered in the evaluation of the seismic safety of these important structures. The earthquake response of gravity dams, including sliding at the interface between the dam base and the foundation rock, is computed using a new numerical method. The Hybrid Frequency Time Domain procedure accounts for the nonlinear sliding behavior of the dam and the frequency-dependent response of the impounded water and the flexible foundation rock. A detailed earthquake analysis of a typical dam is performed using the numerical procedure. The results of a parametric study of typical dams shows how the earthquake-induced sliding is affected by different parameters and by the characteristics of the ground motion. The case study and the parametric study demonstrate that it is necessary to include the effects of dam-foundation rock interaction to obtain realistic estimates of sliding displacement in an earthquake. The sliding displacement is sensitive to the coefficient of friction, especially for moderate to tall dams. Water compressibility and reservoir bottom absorption are important for the sliding displacement of dams on rigid foundation rock, although their effects are less important for dams on flexible foundation rock. For the cases studied, the value of the sliding displacement is relatively small and most dams should be able to tolerate it without considerable damage. |
