Author(s): M. Al-Riffai; I. Nistor
Linked Author(s):
Keywords: Overtopping; Dam breach; Supercritical flow; Slope-retreat; Scale series
Abstract: The breach evolution in an overtopped dam constructed of non-cohesive materials can be observed by following the downslope inflection point which migrates upstream as the breach channel slope retreats downwards due to flow-induced erosion. This control section, which defines the locus of Froude-critical points at the breach entrance, has the form of an arc on the upstream face of dam models which were breached in a wide flume at the University of Ottawa's Hydraulic Laboratory. An approach for determining the discharge over the evolving breach crest was developed based on weir equations and compared to the measured breach outflow. It was found that a correction factor for the discharge estimated using the proposed equations must be incorporated to account for constriction effects due to undercutting in the breach channel entrance as well as submergence effects due to side-slope collapses which occur in the downstream section of the breach channel. This study also examines scaling effects in distorted dam breaching models based on the Froude criterion and explores the possibility of using the void ratio as an alternative scaling criterion for mobile bed models simulating dam breach flows.
Year: 2011