Evaluation of Bridge Scour Research: Pier Scour Processes and Predictions (2011) / Chapter Skim
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Pages 102-111
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100 CHAPTER 6 LEADING METHODS FOR SCOUR-DEPTH PREDICTION 6.1 Introduction This chapter is a review of the existing leading methods for design estimation of pierscour depth. The method best reflecting current understanding of scour processes is identified.
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101 Therefore, the Melville method per se is not considered further in this section. The method proposed by Sheppard and Miller (2006)
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102 xx cd x icd Va DV 053.0 645.0 = (6.4) and xcdV is critical velocity for incipient motion for grain size Dx , given by: 3/16/119.6 xcd DyV x = (6.5)
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103 6.3 The Sheppard-Melville Method (NCHRP Project 24-32) The Sheppard-Melville method builds on the method proposed by Sheppard and Miller (2006)
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104 velocity, Vlp, is computed using a modification of van Rijn's (1993) prediction of the conditions under which the bed planes out.
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105 aspects of the flow field and erosion processes at piers; the Sheppard-Melville method is better reconciled than the Richardson and Davis method. In accordance with the third objective set for this project (Section 1.4)
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106 The Richardson and Davis method, though well-correlated empirically to the available data upon which it is based, has the following limitations: 1. Scour is estimated as proportional to Fr0.43 .
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107 the method has remained essentially the same. According to Richardson et al (1990)
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108 mixed7 . It has not proven straightforward to tune-up the basic equation (based on Froude number)
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109 2. Tailor the simplified forms of the equations for application to common pier forms.
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