The authors present the results of an experimental investigation of local scour at a nonuniform cylindrical pier. A nonuniform pier is one in which the cross-sectional dimension differs over the length of the pier. In this examination, the pier comprised a cylinder of diameter (D) founded on a larger cylinder of diameter (D*), called the foundation. In addition to the parameters that influence scour at a uniform pier, the scour depth at a nonuniform pier is dependent on the ratio D/D* and the depth from the bed level to the top of the foundation. The results help define three scour zones: zone 1 where the foundation is below the bottom of the scour hole and does not affect the scour; zone 2 where the top of the foundation is within the scour hole and reduces the scour; and zone 3 where the top of the foundation is above bed level and increases the scour compared to that at a uniform pier. Different design relationships are presented. The authors introduce the concept of an effective pier size and demonstrate that its use leads to conservative estimates of scour depth for nonuniform piers.


  • English

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  • Accession Number: 00720449
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 28 1996 12:00AM