Prediction of Scour at Bridge Abutments

Because current scour prediction techniques are not applicable to a wide range of field conditions, scour at bridge abutments is often over-predicted. Over-predicting abutment scour may result in construction of unnecessary countermeasures or excessively deep foundations, adding significant costs to bridge construction and maintenance. Most experimental studies of scour around abutments have been conducted in rectangular laboratory flumes with level streambeds. Real river channels are decidedly different from these idealized laboratory conditions. Idealized experiments are representative only of flow around abutments in well-defined incised channels and abutments in wide braided rivers. A limited number of studies have been conducted to consider interaction of flows in compound channels (i.e., channels consisting of both floodplain and main channel sections), and only a very limited number of experiments have been done on abutments that terminate on a floodplain near a main channel. Accepted prediction equations for scour around abutments were developed from a narrow range of conditions and do not incorporate the effects of spill-slope embankment failure into surrounding scour holes. As scour develops at the toe of abutment embankments, soil and rock protection fall into the scour hole. Rock protection or embankment material tends to armor the scour hole, and scour tends to proceed horizontally instead of vertically. This process changes the geometry of the embankment and expands the waterway opening, and is likely to play a dominant role in the mechanics of scour. Inclusion of the spill-slope failure process in model studies will have a substantial effect on the location and depth of scour. Specific information about the mechanics of scour around abutments is needed to substantially improve scour-prediction techniques. Data are needed for flow conditions in which the abutment (embankment) terminates near the main channel. In addition, scour depth and contracted flow velocity-distribution data are needed from experiments that model flow conditions in which the position of the abutment on the floodplain, the geometry and roughness characteristics of the floodplain, and the flow distribution in the main channel and floodplain are varied over the practical ranges of these parameters. The objective of this research is to develop more accurate and comprehensive methodologies for predicting abutment scour in compound channels.


  • English


  • Status: Completed
  • Contract Numbers:

    Project 24-20

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway & Transportation Officials

    444 North Capitol Street, NW, Suite 225
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Reynaud, David

  • Performing Organizations:

    University of Iowa, Iowa City

    102 Church Street
    Iowa City, IA  United States  52242
  • Principal Investigators:

    Spasojevic, Miodrag

    Muste, Marian

    Natao, Tatsuaki

    Ettema, Robert

  • Start Date: 20020412
  • Expected Completion Date: 0
  • Actual Completion Date: 20100930
  • Source Data: RiP Project 6568

Subject/Index Terms

Filing Info

  • Accession Number: 01549325
  • Record Type: Research project
  • Source Agency: National Cooperative Highway Research Program
  • Contract Numbers: Project 24-20
  • Files: RiP
  • Created Date: Dec 31 2014 1:01AM