Unpredictable behaviour of a large arch dam in South Africa

The behaviour of the 88 m high Gariep Dam since 1972 is discussed as well as the various regression methods used to predict behaviour. An in-depth behaviour analysis performed in 2010 revealed that the majority of so-called "unpredictable" inelastic deformations occurred as a result of prolonged periods of low water levels. The observed stepped inelastic displacements as well as possible causes are briefly discussed. In conclusion, suggestions are made for the incorporation of duration-dependent inelastic and/or semi-plastic displacements (due to e. g. surface temperature, poro-plastic and swelling action) in regression models.