CS5A - Concurrent Session 05A: Dam Failures and Incidents Due To Dynamic Ice Loads

A search of dam failure databases such as those maintained by the National Performance of Dams Program and the Association of State Dam Safety Officials shows that they did not include any dam failures due to dynamic ice loads until Spencer Dam failed in 2019. Before the failure of Spencer Dam, it appears that the dam safety industry did not generally consider that ice runs could fail dams. This is supported by the fact that current dam safety best practices do not include procedures for evaluating dams for stability during ice runs. Both the Bureau of Reclamation and the U.S. Army Corps of Engineers Best Practices and Risk Methodology that are used by many dam engineers do not include potential failure modes related to ice runs. While static ice pressure against structures has long been documented as a design loading condition, and while the transportation industry has researched ice impact loading on structures such as bridge piers in rivers, the Dam Safety Industry generally lacks knowledge of how ice runs may impact the safety of dams in cold weather regions and how these dams should be evaluated using dynamic ice loads.

This presentation will describe examples of dam failures and significant incidents related to both static and dynamic ice loads with an emphasis on dynamic ice loads. These examples will be used to illustrate the unique combinations of extreme loads that can occur during a dynamic ice event and provide important information to help engineers formulate new potential failures modes for dams in cold weather regions. Considerations will be provided for evaluating the stability of dams subject to dynamic ice loads. Lessons learned from the evaluation of a significant concrete gravity dam subject to dynamic ice loads will be shared and discussed.