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From page 49... ... 4-1 4.1 Severe Contraction Ratio Initially, four clear-water contraction scour tests were conducted in the 8-ft-wide indoor flume at CSU. For these tests, the contracted section was 2 ft wide by 85 ft long, giving a contraction ratio B2/B1 = 2/8 = 0.25. Read the entire page →
From page 50... ... 4-2 Revised Clear-Water and Live-Bed Contraction Scour Analysis Detailed LiDAR scans were taken at the beginning and end of each test. As an example, a plot of the centerline bed elevations from Test CW_0.25-0.75 is provided in Figure 4-2. Read the entire page →
From page 51... ... Clear-Water Laboratory Testing Results 4-3 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0 10 20 30 40 50 60 70 80 90 El ev ati on , f ee t Station, feet Initial 12 hours 24 hours 30.5 hours Figure 4-2. Bed centerline profiles from LiDAR scans at 0, 12, 24, and 30.5 hours during Test CW_0.25-0.75. Read the entire page →
From page 52... ... 4-4 Revised Clear-Water and Live-Bed Contraction Scour Analysis -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0 10 20 30 40 50 60 70 80 90 Be d El ev . Read the entire page →
From page 53... ... Clear-Water Laboratory Testing Results 4-5 are immediately established in the contracted section once the flow is introduced. The bedforms are irregular, with an amplitude on the order of 0.10 ft to 0.15 ft and a wavelength of 2 ft to 3 ft, resulting in increased flow resistance due to form roughness. Read the entire page →
From page 54... ... 4-6 Revised Clear-Water and Live-Bed Contraction Scour Analysis Figure 4-5 (c) Read the entire page →
From page 55... ... Clear-Water Laboratory Testing Results 4-7 τ0 = 0.03 lb/ft2 to 0.06 lb/ft2. These values suggest that the critical values Vc and τc for the threshold of particle motion are substantially greater than would otherwise be predicted from the standard HEC-18 equations. Read the entire page →
From page 56... ... 4-8 Revised Clear-Water and Live-Bed Contraction Scour Analysis 4.1.4 Scour Depth Summary Observed clear-water equilibrium contraction scour depths and flow depths are summarized in Table 4-3 for the four clear-water contraction scour tests performed with the Severe contraction ratio. 4.2 Moderate Contraction Ratio Following completion of the Severe contraction ratio tests, the flume was reconfigured to a new contraction ratio B2/B1 = 0.50. Read the entire page →
From page 57... ... Clear-Water Laboratory Testing Results 4-9 and sealing the wall to the floor and the joints between wall panels. Filter fabric was placed below the sand bed and partially up the side walls. Read the entire page →
From page 58... ... 4-10 Revised Clear-Water and Live-Bed Contraction Scour Analysis measured along the centerline of the flume; bed elevations were obtained at both the centerline and along the right wall. Figures 4-11 (a) Read the entire page →
From page 59... ... Clear-Water Laboratory Testing Results 4-11 -1.20 -1.00 -0.80 -0.60 -0.40 -0.20 0.00 0.20 0 10 20 30 40 50 60 70 80 90 El ev ati on , ft Station, ft CW_0.50-0.75 Lidar Bed Profiles Initial bed: Centerline Initial bed: Wall Final bed at 18 hours: Centerline Final bed at 18 hours: Wall Figure 4-12. Initial and final bed profiles from LiDAR scan, Test CW_0.50-0.75. Read the entire page →
From page 60... ... 4-12 Revised Clear-Water and Live-Bed Contraction Scour Analysis CW_0.50-0.75 Bed Evolution-Centerline CW_0.50-0.75 Bed Evolution-Wall CW_0.50-0.75 Water Surface Evolution-Centerline 0.50 0.55 0.60 0.65 0.70 0.75 0 10 20 30 40 50 60 70 80 90 El ev ati on (ft ) Station (ft) Read the entire page →
From page 61... ... Clear-Water Laboratory Testing Results 4-13 Test CW_0.50-0.55 Centerline -1.0 -0.5 0.0 0.5 1.0 0 10 20 30 40 50 60 70 80 90 100 El ev ati on ( ft ) Station (ft) Read the entire page →
From page 62... ... 4-14 Revised Clear-Water and Live-Bed Contraction Scour Analysis used in the 1D models correspond to the centerline bed elevations measured from the data collection carriage. Refer to Table 3-4 for the details of the HEC-RAS calibrations for all clear-water tests conducted at the Moderate contraction ratio. Read the entire page →
From page 63... ... Clear-Water Laboratory Testing Results 4-15 flume station 40 ranges from about 0.02 lb/ft2 to 0.07 lb/ft2. These values compare with the final (post-scour) Read the entire page →
From page 64... ... 4-16 Revised Clear-Water and Live-Bed Contraction Scour Analysis and the depth of flow at the tailgate (y2 tailgate) Read the entire page →
From page 65... ... Clear-Water Laboratory Testing Results 4-17 Figure 4-19. Initial and final bed profiles from LiDAR scan, Test CW_0.75-0.95. Read the entire page →
From page 66... ... Figure 4-21. Water surface and bed evolution, Test CW_0.75-0.95. Read the entire page →
From page 67... ... Clear-Water Laboratory Testing Results 4-19 at lower velocity ratios were less significant) (Test CW_0.75-0.95 shown) Read the entire page →
From page 68... ... 4-20 Revised Clear-Water and Live-Bed Contraction Scour Analysis Figure 4-22 (c) Read the entire page →
From page 69... ... Clear-Water Laboratory Testing Results 4-21 Shear-stress profiles were developed from the calibrated HEC-RAS model for each of the three clear-water tests at the completion of each 18-hour run. The results are shown in Figure 4-24 for the centerline measurements. Read the entire page →

From page 49...

... 4-1 4.1 Severe Contraction Ratio Initially, four clear-water contraction scour tests were conducted in the 8-ft-wide indoor flume at CSU. For these tests, the contracted section was 2 ft wide by 85 ft long, giving a contraction ratio B2/B1 = 2/8 = 0.25.