Varying the alveoli slopes of Piano key Weirs: Interests and limitations

peer reviewedPiano Key Weir is a cost effective solution for rehabilitation as well as for new dam project with a high level of constraints (space, flood discharge, reservoir level). Its labyrinth shape permits the evacuation of discharges till four times more important than ogee-crested weirs with the same length at the dam crest, when the use of overhangs permits the building of the auto-equilibrated structure directly on dam crest. If the efficiency of the Piano Key Weir has already been well demonstrated, the definition of its optimal geometry has been still poorly approached. In order to improve the design of the complex geometry of this structure, the study of the influence of the mean geometrical parameters on the discharge capacity is an essential stage. Following a former experimental study of the flow over Piano Key Weirs, highlighting the mean influence of three geometrical parameters, this paper presents the results of an experimental parametric study. These results highlight the influence of the alveoli bottom slopes on the Piano Key Weir release capacity. In this paper, the interests and limitations of the variation of the slopes are explained. Recommendations directly linked to the observation of the experimental models are also provided to improve the design of PKW