FLOOD01242 - Laserfiche WebLink

Home Browse Search

The shape of the upstream edge of the intermediate walls of multibarrel installations is not as important to the hydraulic performance of a culvert as the edge condition of the top and sides. Therefore, the edges of these walls may be square, rounded with a radius of one-half their thickness, chamfered, or beveled. The intermediate walls may also project from the face and slope downward to the channel bottom to act as debris fins as suggested in REC No.9 (15). It is recommended that Chart 9 for skewed inlets not be used for multiple barrel installations, as the intermediate wall could cause an extreme contraction in the downstream barrels. This would result in underdesign due to a greatly reduced capacity. As discussed in Section V, skewed inlets should be avoided whenever possible, and should not be used with side- or slope- tapered inlets. Side-Tapered Inlets Description The selected configurations of the side-tapered inlet are shown in Figure 9. The barrel and face heights are the same except for the addition of a top bevel at the face. Therefore, the enlarged area is obtained by making the face wider than the barrel and providing a tapered sidewall transition from the face to the barrel. Side taper ratios may range from 6:1 to 4:1. The 4:1 taper is recommended as it results in a shorter inlet. The throat and the face are possible flow control sections in the Side-tapered inlet. The weir crest is a third possible control section when a FALL is used. Each of the possible control sections should be sized to pass the design discharge without exceeding the allowable headwater elevation. Plots of the performance of each of the possible inlet control sections along with the outlet control performance curve define the culvert performance. 13-20 e e . , ~ e