MINIMIZING OF SCOUR DOWNSTREAM THE OUTLETS OF THE BOX CULVERT

Local scour downstream the box culverts outlet may cause to a complete failure of the culvert structure. New research is employed to reduce the max scour depth downstream the outlet of the box culvert under a different flow conditions based on an experimental investigation. A sharp edge sill is proposed on a rigid bed to dissipate the flow excess energy. Consequently, a great reduction of the scour hole dimensions is obtained by using the sharp edge sill. The experimental study was carried out using a different positions, heights and shapes of the sharp edge sill with different flow rates as well as tail water depths too. The results indicates that the sharp edge sill is a promising tool to reduce the scour dimensions. The reduction of the scour depths by using the sharp edge sill are 60%, while the reduction in the scour depths are 64%,that is because of using of rigid apron of length 7 times the height of culvert, compared to previous results without rigid bed.