A systems approach to ice loads on concrete dams

• Main Author: Hellgren, Rikard
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: KTH, Betongbyggnad 2022
• Subjects: Ice loads; Ice pressure; Dam safety; Concrete dams; Cold regions; Monitoring; Measurements; Infrastructure Engineering; Infrastrukturteknik; Ice Sheet
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-306937

Dams are mainly used for the storage of water to electricity production and irrigation, or for river regulation. Continuous work to assure a high dam safety level is a prerequisite to minimize the risk for the uncontrolled release of water. An essential part of the safety evaluation of concrete dams is to understand the loads they are exposed to and the expected response of the dam. Under normal conditions, the behaviour of concrete dams is, to a great extent, governed by the ambient variation in temperature and water level. For concrete dams in cold climates, the large variation in ambient temperatures between summer and winter is particularly significant. In addition, these dams may be subjected to a pressure load from the expansion or movement of an ice sheet on the reservoir. The current guidelines for these ice loads are based on the dam's location and state that concrete dams must be designed for a line load of 50-250 kN/m. Thus, the ice load constitutes a significant part of the total load, especially for small dams. Despite its relatively significant impact, the knowledge about ice loads is insufficient, and the magnitude and return period of ice loads constitute one of the greatest uncertainties during stability evaluations of concrete dams. Furthermore, an apparent contradiction is that measurements and models indicate that ice loads are higher than the recommended values. Simultaneously, there are no reported dam failures where the ice-load has been addressed as the reason for the breach. To increase the knowledge about ice loads and the structural behaviour of concrete dams, this thesis applies an approach where the ice and the dam are parts of a structural system. The thesis contains six studies investigating the dam's, the ice's or the system's response to external loads. Studies of the dam are aimed at increasing the understanding of the normal behaviour of concrete dams. Studies of ice loads include measurements, and a major contribution from this project is the development of a 1$\times$3 m$^2$ ...