An overview of trends and regional distribution of thermal ice loads on dams in Norway

Norway has over 3000 dams, over half of which are concrete dams [1]. Static ice loads are considered as part of dam design and during period safety review. They present a significant fraction of the total design load of low dams, also called small dams, common in Norway [1]. Ice loads are traditionally considered driven by the thermal expansion of ice, although measurements showed that slow water level fluctuations covering a range similar to ice thickness have the potential to cause loads of similar magnitude [2]. Commonly used static ice loads in dam design include 100 to 150 kN/m in Norway, regionally-dependent 50 to 200 kN/m in Sweden, ice thickness-dependent 150 to 220 kN/m in Canada, and at least up to 300 kN/m in Russia [3]. While the climate in Norway ranges from temperate to polar, no specific rules are in place to help select design ice loads based on regional differences. Instead, climatic conditions may be considered on a case-by-case basis. To-date, no global failures of dams due to ice loads have been reported in Norway [1], raising the question whether current design practices are too conservative.