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NCHRP Report 516: Pier and Contraction Scour in Cohesive Soils (2004)
National Cooperative Highway Research Program (NCHRP)

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Wang, J, Briaud, J-L, Li, Y, Chen, H-C, Nurtjahyo, P, Transportation Research Board. "9.6 Output of the SRICOS-EFA Program." NCHRP Report 516: Pier and Contraction Scour in Cohesive Soils. Washington, DC: The National Academies Press, 2004.

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Page
84
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Page
84
Front Matter (R1-R10)
Summary (1-7)
1.4 Why Was This Problem Addressed? (8-8)
1.5 Approach Selected to Solve the Problem (9-9)
2.4 Erodibility and Correlation to Soil and Rock Properties (10-13)
3.3 EFA Test Data Reduction (14-14)
3.4 EFA Precision and Typical Results (15-16)
4.2 Small Flood Followed by Big Flood (17-17)
4.3 Big Flood Followed by Small Flood and General Case (18-18)
4.4 Hard Soil Layer Over Soft Soil Layer (19-20)
4.6 Equivalent Time (21-21)
4.7 Extended and Simple SRICOS-EFA Method (22-23)
4.8 Case Histories (24-25)
4.9 Predicted and Measured Local Scour for the Eight Bridges (26-28)
4.10 Conclusions (29-29)
5.4 Measuring Equipment (30-31)
5.5 Soils and Soil Bed Preparation (32-32)
5.6 Flume Tests: Procedure and Measurement (33-33)
5.8 Shallow Water Effect on Maximum Pier Scour Depth (34-35)
5.9 Shallow Water Effect on Initial Shear Stress (36-36)
5.11 Pier Spacing Effect on Maximum Scour Depth (37-37)
5.12 Pier Spacing Effect on Initial Scour Rate (38-38)
5.15 Pier Shape Effect on Initial Scour Rate (39-39)
5.18 Attack Angle Effect on Maximum Scour Depth (40-41)
5.20 Attack Angle Effect on Scour Hole Shape (42-42)
5.21 Maximum Scour Depth Equation for Complex Pier Scour (43-44)
6.2 Existing Knowledge on Numerical Simulations for Scour (45-45)
6.5 Shallow Water Effect: Numerical Simulation Results (46-46)
6.6 Shallow Water Effect on Maximum Shear Stress (47-47)
6.7 Pier Spacing Effect: Numerical Simulation Results (48-48)
6.9 Pier Shape Effect: Numerical Simulation Results (49-50)
6.10 Pier Shape Effect on Maximum Shear Stress (51-51)
6.11 Attack Angle Effect: Numerical Simulation Results (52-52)
6.12 Attack Angle Effect on Maximum Shear Stress (53-53)
6.13 Maximum Shear Stress Equation for Complex Pier Scour (54-55)
7.3 Flume Tests and Measurements (56-56)
7.4 Flume Tests: Flow Observations and Results (57-58)
7.5 Flume Tests: Scour Observations and Results (59-59)
7.6 Maximum and Uniform Contraction Depths for the Reference Cases (60-62)
7.7 Location of Maximum Contraction Depth for the Reference Cases (63-63)
7.8 Correction Factors for Transition Angle and Contraction Length (64-64)
7.9 SRICOS-EFA Method Using HEC-RAS Generated Velocity (65-65)
7.11 Scour Depth Equations for Contraction Scour (66-67)
8.3 Transition Angle Effect: Numerical Simulation Results (68-68)
8.4 Contracted Length Effect: Numerical Simulation Results (69-71)
8.6 Maximum Shear Stress Equation for Contraction Scour (72-75)
9.3 The Integrated SRICOS-EFA Method: Step-by-Step Procedure (76-80)
9.5 The SRICOS-EFA Program (81-83)
9.6 Output of the SRICOS-EFA Program (84-84)
10.4 Gill (1981) Database: Contraction Scour (85-87)
10.5 Remarks (88-88)
11.2 Preparation of the Future Hydrographs (89-89)
11.3 Risk Approach to Scour Predictions (90-90)
11.4 Observations on Current Risk Levels (91-92)
12.2 Example 2: Single Rectangular Pier with Attack Angle and Approaching Hydrograph (93-94)
12.3 Example 3: Group Rectangular Piers with Attack Angle and Approaching Constant Velocity (95-98)
12.4 Example 4: Contracted Channel with 90-Degree Transition Angle and Approaching Constant Velocity (99-102)
12.5 Example 5: Contracted Channel with 60-Degree Transition Angle and Approaching Hydrograph (103-104)
12.6 Example 6: Bridge with Group Piers and Contracted Channel with Hydrograph in Contracted Section (105-110)
13.1 Conclusions (111-112)
13.2 Recommendations, (113-113)
References (114-115)
Nomenclature (116-117)
Unit Conversions (118-118)
Appendix A - Photographs from the Flume Tests (119-125)
Abbreviations used without definitions in TRB publications (126-126)

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84 TABLE 9.2 Example of SRICOS-EFA Program output file data can be either in the metric system or U.S. customary sys- Woodrow Wilson Bridge Flow Velocity Chart tem; the output also can be in either system. The User's Man- (from 1960 to 1998) ual for SRICOS-EFA is presented in Appendix D of the 3 research team's final report, which is available from NCHRP. 2.5 Velocity (m/sec) 2 9.6 OUTPUT OF THE SRICOS-EFA PROGRAM 1.5 Once the program finishes all of the computations success- 1 fully, the output file is created automatically. The output file includes the following columns: time, flow velocity, water 0.5 depth, shear stress, maximum scour depth (pier, contraction, or 0 total), and instantaneous scour depth (pier, contraction, or 19601963196619681971197419771980198319851988199119941997 total). The first few days of a typical output file of the program Year are shown in Table 9.2. For this example, the critical shear stress was 4 N/m2; as can be seen, no scour occurred until the Scour Depth Vs Time 7000 velocity was high enough to overcome the critical shear stress on day 11. The format of the output file is a text file. This file 6000 Scour Depth (mm) can be used to plot a number of figures (Figure 9.10). The most 5000 commonly plotted curves are water velocity versus time, water 4000 depth versus time, shear stress versus time, and scour depth ver- 3000 sus time. The scour depth versus time curve indicates whether 2000 the final scour depth Zfinal (scour depth at the end of the hydro- 1000 graph) is close to the maximum scour depth for the biggest flood in the hydrograph Zmax or not. Typically, in sand the 0 1960 1965 1970 1975 1980 1985 1990 1995 answer is yes, but in low erodibility clays the difference is sig- Time (year) nificant enough to warrant the analysis in the first place. Kwak et al. (2001) showed the results of a parametric analysis indi- Figure 9.10. Example of plots generated from SRICOS- cating the most important parameters in the prediction process. EFA output.