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Reevaluation of the Adjustment Factor for Coarse Bed Material Under Clear-Water Scour Condition

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Project Abstract: 

The study will analyze the effect of pier scour coarse bed material. If the riverbed material has more large sand particles than fine sand, pier scour will be reduced because large particles will withstand the hydraulic dislodging forces and therefore armor the scour hole. If the particle distribution consists of more fine sand than large particles, pier scour will be greater. This research will study the influence of sand particle distribution on bridge pier scour. The goal is to develop an improved scour equation for coarse sand particle distribution by revisiting and improving the methodology suggested in Hydraulic Engineering Circular No. 18; a methodology that is difficult to apply.


The study will develop a new pier scour equation for course bed material. The new design procedure will replace the outdated coarse bed material adjustment factor in the current pier scour equation in Hydraulic Engineering Circular No. 18 "Evaluating Scour at Bridges."

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Start Date: 
Sunday, February 1, 2009
End Date: 
Friday, September 30, 2011
Public Access Plan: 
J. Sterling Jones Hydraulics Research Laboratory
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