بررسي آزمايشگاهي اثر تيغه ي افقي بر توپوگرافي بستر در خم 90 درجه

Experimental Investigation on the Effects of Horizontal Footing on Topography of Bed in 90° Bend

The outer banks in river bends are subject to sever bank erosion due to secondary flows. Therefore, it is essential to have some measurements for protection. The protection must be based on maximum scour hole. Any measurements to reduce the scour hole would be beneficial for protection. In this paper the effect of horizontal footing on reduction of scour hole has been investigated. To reach such goals, an experiment with a 90 degree flume was carried out and series of horizontal footing were installed at outer bank in four different elevations of 0, 20, 40 and 60 percent of maximum scour depth. By comparison of the bed topography with and without footing; a maximum scour reduction of more than 44.5% was obtained with footing installed at elevation of 40% of the maximum scour depth. The results of this study reveal that the point of maximum scour hole has been displaced from the outer bank to the center of the flume.