Impact of Near-Fault vs. Far-Field Ground Motions on the Seismic Response of an Arch Dam with Respect to Foundation Type

摘要

In the present paper, the impact of input ground motion characteristics on the seismic response of a typical concrete arch dam has been investigated by relying on the foundation numerical model. For this purpose six ground motions, including near-fault and far-field recordings, with various characteristics in the acceleration response spectrum, have been used to analyze the coupled system. Three different options have been introduced for the dam-foundation interaction: 1) foundation rock is assumed to be rigid; 2) foundation rock is modelled as a massless medium; and 3) a massed foundation is assumed with the inclusion of infinite elements at the far-end boundaries. The reservoir medium is assumed to be compressible, and has been modelled according to the Eulerian approach. It has also been observed that modelling the foundation as a massed element decreases stresses relative to the massless model, while use of a rigid foundation model leads to stress concentration at the dam-foundation interface. In all these foundation types, near-fault ground motions have led to higher responses than far-field motions, especially for the upper parts of the dam body, with less scattering of results in far-field ground motion.