DISCHARGE RATING CURVE AND SCALE EFFECTS CORRECTION IN MORNING GLORY SPILLWAYS

摘要

Dam spillways are the structures that lead rightly and safely the outflow downstream, so that the dam integrity can be guaranteed. Many accidents with dams have been caused by an inadequate spillway design or insufficient capacity. This situation is particularly important in embankment or rockfill dams, because the possibility of overtopping failure of the dam. The morning glory spillway may be used when there is not available space for a conventional spillway. Engineers use physical modeling to design this kind of structures, and therefore scale effects can cause a difference between model and prototype discharge rating curve. This paper has the objective of analyze the discharge flow rating curve in a vertical shaft with morning glory inlet and to correct scale effects for low heads. An experimental study has been carried out, using the spillway model of Paraitinga Dam in 1:51,02 scale. As a result equations are proposed in order to correct the discharge coefficient in the discharge rating curve for low heads.