Uplift Considerations for Concrete Gravity Dams

Uplift forces along foundation joints or improperly bonded concrete joints are a widely recognized contributor to failure modes for concrete gravity dams. The industry-wide inclusion of uplift forces in the design and evaluation of concrete dams was predated by several dam failures (e.g., Bouzey Dam, Austin Dam, St. Francis Dam) that can be at least partially attributed to a lack of understanding of these forces. This paper provides a summary of the current state-of-the-practice in application of uplift forces on concrete dams and a summary of a panel discussion held at the 2016 national conference of the Association of State Dam Safety Officials (ASDSO). The summary includes the most recent federal guidelines and standards used in design and evaluation of concrete dams, including Federal Energy Regulatory Commission (FERC), Bureau of Reclamation (Reclamation), and U.S. Army Corps of Engineers (USACE) guidelines. The panel discussion section summarizes the discussions at the ASDSO conference including audience questions and the panelists’ responses. Particular attention is given to clarifying application of uplift pressures for concrete dams with foundation and body drains, and to methods for adjusting uplift pressures for flood, earthquake, and post-earthquake loading, as well as cracked base analysis.