Seismic analysis of a concrete gravity dam considering dam-water-sediment-foundation interaction

The dynamic behaviour of a concrete gravity dam-impounded water-sediment-foundation system is very complex under seismic loading condition. This study is focussed on the investigation of the effects of variations in the material properties of a dam monolith and foundation bed, the consideration of with and without–slip conditions at the dam-foundation interface, and the variation in slope of sediment bed on the seismic behaviour of a concrete gravity dam. A finite element model of the Koyna dam has been developed in the computer software ABAQUS to investigate the dam-reservoir-sediment-foundation interaction behaviour. The Koyna earthquake excitations in both horizontal and vertical directions of the dam have been used as the input data for the dynamic analysis. The main parameters investigated are contact pressure, friction shear stress at dam heel, heel stresses, crest displacement and accelerations, and tension damage. The findings of this numerical study are also compared with the results predicted from the models proposed by Westergaard and Darbre using the added mass concept for the reservoir effect.