Bridge Pressure Flow Scour for Clear Water Conditions

The equilibrium scour at a bridge caused by pressure flow with critical approach velocity in clear-water simulation conditions was studied both analytically and experimentally. The flume experiments revealed that (1) the measured equilibrium scour profiles under a bridge are more or less consistent across the channel width; (2) all the measured scour profiles can be described by two similarity equations where the horizontal distance is scaled by the deck width and the local scour is scaled by the maximum scour depth; (3) the maximum scour position is located under the bridge and at a location approximately 15.4 percent of the deck width from the downstream edge of the deck; (4) scour begins at approximately one deck width upstream of the bridge, and deposition begins at approximately 2.5 deck widths downstream of the bridge; and (5) the maximum scour depth decreases with increasing median sediment size but increases with higher levels of deck inundation. The analytical analysis shows that (1) bridge scour can be divided into three cases: downstream unsubmerged, partially submerged, and totally submerged; (2) for downstream unsubmerged flows, the maximum scour depth is an open channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied; and (3) for partially and totally submerged flows, the maximum scour depth can be described by scour and inundation similarity numbers, which has been confirmed by experiments with two sediment sizes (0.039 and 0.078 inches (1 and 2 mm)) and two types of decks with three and six girders, respectively. For application, a design and field evaluation procedure with examples is presented, including the maximum scour depth and scour profile.

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  • Corporate Authors:

    GKY and Associates, Incorporated

    4229 Lafayette Center Drive, Suite 1850
    Chantilly, VA  United States  20151

    University of Nebraska, Lincoln

    312 N 14th Street, Alexander Building West
    Lincoln, NE  United States  68588-0430

    Federal Highway Administration

    Office of Infrastructure Research and Development
    6300 Georgetown Pike
    McLean, VA  United States  22101
  • Authors:
    • Guo, Junke
    • Kerenyi, Kornel
    • Pagan-Ortiz, Jorge E
  • Publication Date: 2009-10


  • English

Media Info

  • Media Type: Web
  • Edition: Laboratory Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 59p

Subject/Index Terms

Filing Info

  • Accession Number: 01152678
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-HRT-09-041
  • Files: TRIS, USDOT
  • Created Date: Mar 16 2010 8:12AM