Author(s): Y. Darama
Linked Author(s):
Keywords: Stepped Spillway; Hydraulic model; Cine dam
Abstract: An experimental study was conducted to study the Hydraulics of the Cine Dam's RCC type stepped spillway by means of physical modelling. Two physical models of the Cine dam stepped spillway were constructed for this purpose. The first one is a 1/60 scale model which covers the whole dam site, so that the general hydraulic conditions could be investigated. Experiments on the model during its original project condition showed that structural modifications were needed to eliminate severe hydrodynamic instabilities caused by the form of the side channels for Q>500 m3/s. Having done the modifications on the model, data obtained from the 1/60 scale model experiments were analyzed to determine the flow regime in the spillway. Analysis of the data showed that the flow regime in the spillway was in nappe flow regime when the spillway discharges were less than 175 m3/s, and in skimming flow regime when the spillway discharges were greater than 350 m3/s. Observations on the spillway to determine the point of inception and observed flow conditions agreed well with the method described by Chanson (2000). To determine the point of inception more accurately and to study detailed hydraulic conditions, the second 1/30 scale sectional model was constructed. Experiments conducted on this model showed that the results obtained from the 1/60 scale model are also accurate enough to determine the hydraulic behaviour of the Cine Dam RCC type stepped spillway. Analysis of the data obtained from the 1/30 scale model showed that as the value of spillway discharge decreased the amount of energy dissipated by the spillway steps increased.
Year: 2003