EARTHQUAKE PERFORMANCE OF CONCRETE SLAB ON CONCRETE FACED ROCKFILL DAM INCLUDING HYDRODYNAMIC EFFECTS

Concrete faced rockfill (CFR) dams are usually designed ignoring hydrodynamic pressures and also friction between the concrete slab and the rockfill. In this study, this combination is considered under seismic excitations. The main goal of the study is to investigate earthquake performance of concrete slab on CFR dam comprehensively. For this purpose, two dimensional finite element model of Torul CFR Dam is employed. Concrete slab-rockfill interface is considered as including welded contact (Case 1) and friction contact (Case 2) in finite element analyses. Earthquake performance of the concrete slab is determined according to empty and full reservoir cases. Hydrodynamic pressure of reservoir water is considered using fluid finite elements based on the Lagrangian approach. In the materially nonlinear time-history analyses, the Drucker-Prager model is utilized for concrete slab and multi-linear kinematic hardening model is utilized for rockfill zones and foundation rock. East-west component of 1992 Erzincan earthquake is used in seismic analyses. Earthquake record with peak ground acceleration (pga) of 0.496 g is scaled to 0.1 g, 0.2 g, 0.3 g and 0.4 g in time-history analyses. It is seen that earthquake performance of the concrete slab is depended on the magnitude enormity of the earthquake. As the pga of the earthquake increase, earthquake performance of the concrete slab decrease. Although hydrodynamic pressure has fairly less effect on earthquake performance of the concrete slab in Case 1, it has apparent influence in Case 2.