Start Date
4-30-2025 1:30 PM
Description
Stepped chutes have become commonplace in embankment dam rehabilitation projects due to project economy, constructability, and improved chute energy dissipation. Consequently, for applications where a stilling basin is merited the interaction of stepped chutes and stilling basins is of high interest. A commonly used stilling basin type for many smaller embankment dams, the St. Anthony Falls stilling basin (SAF), has no specific hydraulic design guidance for use downstream of a stepped chute. Therefore, this study was conducted at the Utah Water Research Laboratory in a flume with 0.1 m tall steps, a total drop height of 1.8 m, and an embankment slope of 3H:1V, with flow terminating in a SAF basin designed for a Froude number of 4.0. Basin performance for laboratory unit discharges from 0.32 to 0.69 m2/s and incoming Froude numbers from 3.7 to 4.0 were evaluated. Key observations included water surface profiling, basin sensitivity to downstream tailwater, and hydrodynamic pressures acting on the basin floor and baffle blocks, including pressure fluctuations. This work aims to provide additional insights and guidance to engineers when selecting a stepped overtopping protection scheme coupled with a hydraulic jump stilling basin.
Included in
Hydraulic Measurements in a SAF Stilling Basin With a Stepped Chute for Embankment Protection
Stepped chutes have become commonplace in embankment dam rehabilitation projects due to project economy, constructability, and improved chute energy dissipation. Consequently, for applications where a stilling basin is merited the interaction of stepped chutes and stilling basins is of high interest. A commonly used stilling basin type for many smaller embankment dams, the St. Anthony Falls stilling basin (SAF), has no specific hydraulic design guidance for use downstream of a stepped chute. Therefore, this study was conducted at the Utah Water Research Laboratory in a flume with 0.1 m tall steps, a total drop height of 1.8 m, and an embankment slope of 3H:1V, with flow terminating in a SAF basin designed for a Froude number of 4.0. Basin performance for laboratory unit discharges from 0.32 to 0.69 m2/s and incoming Froude numbers from 3.7 to 4.0 were evaluated. Key observations included water surface profiling, basin sensitivity to downstream tailwater, and hydrodynamic pressures acting on the basin floor and baffle blocks, including pressure fluctuations. This work aims to provide additional insights and guidance to engineers when selecting a stepped overtopping protection scheme coupled with a hydraulic jump stilling basin.