Evaluation of SRICOS Method on South Dakota Cohesive Soils

The method currently used by South Dakota Department of Transportation (SDDOT) for designing bridge foundations is Hydraulic Engineering Circular No. 18 (HEC-18). and regressions regression equations. This method is generally regarded as overly conservative due to the fact that scour predictions for cohesive soils are based on laboratory experiments for cohesionless material. The greater scour resistance of cohesive soils may results in bridge foundation designs that are overly conservative. This and have increased cost that could be avoided if more accurate scour prediction methods for cohesive soils were available to design engineers. Work completed by Texas Transportation Institute in 2004 on NCHRP Project 24-15 and published in NCHRP Report 516 using on the SRICOS (Scour Rate In COhesive Soils) method demonstrates that erosion rates for cohesive soils can be are lower than for cohesionless soils. The scour depth in cohesive soils is also dependent upon the duration of the flow.. The testing that this work is based on was done in Texas and one site on the Potomac River near Washington D.C. These results maybe may be valid for cohesive soils in South Dakota, but no verification has been completed to confirm that this method is acceptable to for use in South Dakota. The SRICOS Method could provide potential cost savings and increased confidence levels if testing was done on cohesive soils in South Dakota. The method should also be examined with small water sheds and ungaged streams. as well as determining Sensitivity analysis needs to be conducted to determine the critical input parameters Research Objectives: 1) Determine if scour prediction of SRICOS program is comparable with existing scour data in cohesive soils. 2) Determine impacts of small water sheds on SRICOS and evaluate sensitivity. 2) 3) Evaluate sensitivity and determine critical input parameters to SRICOS program. 3) Determine applicability of SRICOS for use on small water sheds and ungaged streams. Research Tasks: 1) Meet with the technical panel to review project scope, discuss issues, and present tentative review the work plan. Researchers will provide minutes of meeting. 2) Conduct a literature search which will include flow-frequency predictions for small water sheds and ungaged streams and compare the results with other states as they relate to use of SRICOS (Scour Rate In COhesive Soils) to evaluate bridge scour. At a minimum this will include surrounding states. 3) Through collaboration with SDDOT and USGS identify three sites for verification of SRICOS method. 4) Conduct site investigations, collect minimum of four Shelby tube soil samples per site, and complete drilling log of sites identified in task Task 3. All data collected will be included in final report. Continuous sampling will be conducted from flow line down to foundation elevation. 5) Conduct Erosion Function Apparatus (EFA) testing, on Shelby tube samples (minimum of four samples per site), grain size analysis, soil classification with AASHTO standard designation, and  Atterberg limits as required. Report on Shelby tube samples. soil classification with AASHTO standard designation. 6) Obtain hydrologic data (estimate if none existing) and run Hydrologic Engineering Centers River Analysis System (HEC- RAS) on data to obtain estimate flow velocity at bridge pier sites identified in task 3. 7) Run the SRICOS program on using data obtained from previous tasks and sites identified in task 3. Compare these scour predictions with predictions from existing data. 8) Conduct sensitivity analysis on data from task 7 and identify critical input parameters in SRICOS program. 9) Meet with technical panel to review drilling information, soil testing results, SRICOS predictions, and other significant data that has been collected to date. 10) Provide guidance on use of SRICOS for predicting bridge scour in small watersheds and ungaged streams. 11) Prepare a final report and executive summary of the prior research literature survey, research methodology, findings, conclusions and recommendations. 12) Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.


    • English


    • Status: Active
    • Funding: $120000.00
    • Contract Numbers:


    • Sponsor Organizations:

      South Dakota Department of Transportation

      Transportation Building, 700 E Broadway
      Pierre, SD  United States  57501
    • Project Managers:

      Ormesher, Daris

    • Performing Organizations:

      South Dakota State University, Brookings

      Department of Civil and Environmental Engineering
      Brookings, SD  United States  57007
    • Principal Investigators:

      Jones, Allen

      Ting, Francis

    • Start Date: 20070101
    • Expected Completion Date: 0
    • Actual Completion Date: 20091030
    • Source Data: RiP Project 26325

    Subject/Index Terms

    Filing Info

    • Accession Number: 01461463
    • Record Type: Research project
    • Source Agency: South Dakota Department of Transportation
    • Contract Numbers: SD2006-08
    • Files: RIP, STATEDOT
    • Created Date: Jan 3 2013 1:46PM