Distribution of Pressures on Modified Stepped Spillway by Using Toothed-Steps

Abstract

 A new stepped spillway shape was used in experimental work under the skimming flow regime by adding block (tooth) on the step.  The tooth-stepped spillway reduces the positive and negative pressure on steps close to the crest by a large amount and especially at high discharge.  When the spacing between tooth increase the pressure along the chute will have bad distribution compare to the traditional model.In the present study a new steeped spillway shape at which "toothed steps" have been adopted instead of traditional steps to enhance the amount and distribution of water pressure along the chute of the stepped spillway. Experiments were conducted under a skimming flow regime, on five physical models of spillway one of which consisted of traditional steps used as a base model. For all investigated models, the chute angle was 45° with fourteen steeps each of 3cm height. Generally, the results show that the new shape models enhance the pressure distribution and reducing the potential for negative pressures along the chute, as well as, reducing the values of positive pressures that usually impact the tread. Specifically, close to the crest, the differences in pressure values being clearly large between the toothed steps modelsand the traditional steps. The new configurations of steps reduce the positive pressures between 116.66% to 1.28 % and the negative pressures were generally close to zero.