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A broken headwall for increasing the working efficiency of box culverts

Research Authors
Aly T. Edris, Ashour M. Abdelsalam
Research Department
Research Year
2017
Research Journal
International Water Technology Journal, IWTJ
Research Publisher
International Water Technology Journal
Research Vol
Vol. 7-No. 2
Research Rank
1
Research_Pages
133-142
Research Website
http://iwtj.info
Research Abstract

Since inclined headwalls proved promising good results in increasing the performance efficiency of the under-desert road culverts, and so protecting such roads against overtopping and flooding (Ashour et al., 2016). Using headwalls with inclination angle less than 45° will be so expensive due to its big length for reaching the water levels, so in this experimental study, we present a trial for introducing an economical solution for using such inclined headwalls, to score the two needed goals (more culvert performance efficiency, for desert roads protection and at the same time, with minimum cost). The technical idea tested here is to use a broken headwall consists of two parts; the first part is an inclined part just over the top point of the culvert, while the second part which will be over that inclined part will be vertical and extends some distance over the water surface. This study is divided into two trends, the first one is focusing on obtaining the optimum inclination angle (θ), of the inclined lower part of the tested headwall, and the second trend concerns with the length (L) of that inclined part (as a function of the culvert inside height "d") after which the vertical part begins. Six angles of inclination ranging from 15° to 90° were tested in addition to the culvert without any headwalls (projected culvert) as a reference. In the second pivot, five models of broken headwalls of lower inclined part of length ranging as L/d = 0.5, 1.0, 1.5, 2.0, and 2.5 were examined with the recommended inclination angle. Experiments carried out using the introduced new shape of the headwall in both upstream and downstream sides (at the entrance and exit of the culvert). Through a total of 315 experimental runs, 30° inclination angle for the introduced headwall in both culvert's entrance and exit, proved the best among all the tested angles. Also, the relative length of the inclined part (L/d) =2.5 showed the best economic relative length for the lower inclined part among all the tested relative lengths.