CE 462HEC-RAS Final Project

Zahin ChowdhuryJoe SamolewiczYiang Xiao

May 6, 2015

ContentsI.Introduction3II.Geometry of Flow4III. Structure 1 Pipe7IV. Structure 2 Box Culvert10V.Structure 3 Bridge12VI. Conclusion14

I. IntroductionIn this project, we were given a map of Green Garden Road, which contains a river that flow alongside the roads in the map. In this project we designed three different structures to travel across the river. The three hydraulic structures we designed are a corrugated metal pipe, a box culvert, and a bridge. The map was made in AutoCAD, from where we took data for multiple cross sections and designed the structure in HEC-RAS to test flow. Below is the original map used to create the project.

Figure 1 CAD Model of Green Garden Road

II. Geometry of FlowFrom the AutoCAD file, we took ten cross sections along the river. We created an alignment along the river and then created sample lines from where we developed the cross section. We then imported this information to HEC-RAS to create our geometry. We then created a plan that includes flow rates ranging from 60 cfs to 150 cfs at 10 cfs interval. We then created profile view of the river, which we used to calculated the S0 values upstream and downstream at normal depth. The S0 values calculated were 0.038 for the upstream and 0.026 for the downstream. Below are the cross sections as viewed on HEC-RAS and AutoCAD drawing of where cross sections were taken from.Cross Section station 0+00

Cross Section station 1+00

Cross Section station 2+00

Cross Section station 3+00

Cross Section Station 5+00

Cross section Station 6+00

Cross Section station 7+00

Cross Section station 8+00

Cross Section station 9+00

Cross section station 10+00

Figure 2 Cross Sections taken from AutoCad

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Figure 3 Profile view of river

III. Structure 1 PipeThe first structure we designed for crossing the river was a corrugated metal pipe with a 3 foot diameter. The pipe was placed at station 0+80. From the AutoCAD file of Green Garden Road, this station had least amount of elevation change along the bank and requires the least amount of work due to the lack of trees around the surrounding. Due to the pipe having a small cross sectional area, the water would over flow over the roadway unless the elevation is reasonably brought up 10 feet above the bank station. Below is the cross sectional views of pipe at the upstream and downstream ends as well as the rating curve of the pipe.

Figure 4 Cross Section of Pipe

Figure 5 Rating Curve of Pip

Figure 6 Profile with pipe flow

IV. Structure 2 Box CulvertThe second option we analyzed was an 8x8 box culvert. We placed the box culvert at the same location as pipe. The cross section was much larger than the pipe, so there was no problem of overflow onto roadway. Also, there was far less concrete needed to create the roadway, which makes it more feasible than the pipe. The following two figures show the cross section views of the culvert and the rating curve.

Figure 7 Cross Section of Box Culvert

Figure 8 Rating Curve of Box Culvert

Figure 9 Profile with box culvert

V. Structure 3 BridgeThe third hydraulic structure we designed was a bridge. The bridge was placed at the same station as the other two culvert structures. The bridge was modeled to have two piers with a uniform width of 2 feet. The following two figures show the cross section views of the designed bridge and the rating curve of the structure.

Figure 10 Cross Section of Bridge

Figure 11 Rating Curve of Bridge

Figure 12 Profile with bridge

VI. ConclusionAll three proposed hydraulic structures were designed to be placed at the same station. From the analysis of the three designed structures, we need to decide which structure is the optimal choice for this project. Since the pipe has a small diameter, the roadway needed to be brought up extra 10 feet in order to prevent overflow caused by large flow rates. Therefore, this structure would require a lot more concrete and other materials to build. In addition, the water surface elevation increases drastically, in comparison to the other two structures, as flow rate increases. This makes the pipe an unideal design for the given situation. For the box culvert and the bridge, the rating curves are somewhat similar. However, a bridge is generally a more complex structure than a box culvert and requires more materials, labor, and money to construct. Therefore, for the given project, we believe that the box culvert is the best design among all three, because of its relatively better performance under different flow rate scenarios as well as relatively less amount of materials and potential cost.