The Impact of Climate Change on the Structural Safety of Concrete Arch Dams Subject to AAR

Global warming is expected to increase average temperatures in South Africa by up to 3 ℃ by 2050, compared to 1961–2000. This increase in temperature will change the environmental loading on arch dams, which are sensitive to closure temperature. In addition, the rate of concrete swelling due to chemical reactions such as aggregate alkali reaction (AAR) is expected to increase. This paper presents the results of a study of the impact of climate change on two double curvature arch dams in South Africa. One of the dams is subject to concrete swelling due to AAR. The subject dam is Kouga Dam located on Kouga River in the Eastern Cape Province of South Africa. The dam has been subjected to AAR since the early 1970s. The study showed that long-term temperature increase will induce permanent upstream displacements leading to an increase in tensile stresses on the dam wall. In addition, increased temperature will accelerate the swelling of dams due to chemical reactions, further increasing both tensile and compressive stresses in the dam wall. These effects, in combination with the hydrostatic load, may lead to cracking of the dam wall in critical locations.