Arch dam static and dynamic modelling with discrete elements

Abstract

The safety of concrete arch dams depends to a large extent on the soundness of the foundation rock mass. The large arch dams presently under design and construction apply very significant loads to their abutments and foundations. The assessment of the foundation stability requires the analysis of the potential failure mechanisms defined by the major rock mass discontinuities and joint sets. For dams located in areas of intense seismic activity, the analysis needs to take into account the potential effects of earthquakes, not only on the concrete arch, but also in the nearby rock discontinuities. The discrete element method is a major numerical tools for discontinuum modelling, allowing the analysis of block systems defined by multiple joint planes. In the paper, the key issues involved in its application to arch dam foundations are reviewed. In particular, the representation of the discontinuities in models intended for failure analysis is discussed. The evaluation of safety factors under static loading is addressed. The framework for seismic analysis of arch dams is also examined, namely the dynamic boundary conditions. Options to analyse the dynamic dam-water interaction and model calibration issues are discussed, based on practical examples.