New Solutions to Reduce Cavitation Damage to Spillways and Stilling Basins

ABSTRACT ONLY - Cavitation damage to concrete surfaces on hydraulic structures such as spillways and stilling basins continues to be a concern for facilities throughout the world. The severity of these issues range from additional repair and maintenance costs to dam safety concerns. Solutions such as spillway air slots, developed largely in response to severe cavitation at Hoover and Glen Canyon dams, have been effective at preventing cavitation damage in several large spillways but may not be applicable to every facility or situation. With advancements in concrete technology, additional solutions that include both air entrained into the flow and high strength materials to resist cavitation damage may offer significant benefits for a wider range of facilities and applications. Recent studies at the Bureau of Reclamation’s Concrete and Hydraulics laboratories, in collaboration with Brazilian laboratories, have investigated cavitation damage for a range of concrete strengths, with and without air mixing. Quantitative data and visual results from the laboratory show that strong correlations exist between cavitation damage and concrete strength as well as air entrained into the flow which dramatically reduces the aggressiveness of the cavitation. Laboratory results, combined with historic field data of cavitation on several spillways from Reclamation and Brazil are being used to develop guidance for concrete design to be used in repair or new construction to reduce cavitation damage.