Evaluation of Bridge-Scour Research: Abutment and Contraction Scour Processes and Prediction (2011) / Chapter Skim
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1 EXECUTIVE SUMMARY INTRODUCTION The objective of this study is to review the present state of knowledge regarding bridgeabutment scour and evaluate the leading methods currently used for estimating design scour depth. It focuses on research information obtained since 1990, and that must be considered in updating the scour-depth estimation methods recommended by AASHTO1 , and used generally by engineering practitioners.
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2 overarching design philosophy buttressed by fulfilling carefully focused and defined research needs. OBJECTIVES The study's specific objectives are: 1.
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3 RESEARCH FINDINGS At the outset, it was necessary to re-examine the definition of abutment scour because of its close association and interaction with contraction scour. Abutment scour is defined herein as scour at the bridge-opening end of an abutment, and directly attributable to the flow field developed by flow passing around an abutment.
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4 far back from the main channel. Given the floodplain resistance to scour, this scour condition usually occurs as clear-water scour and can result in soil and riprap sliding into the scour hole as in Scour Condition A; 3.
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5 Classification by Parameter Groups From the dimensional analysis of the abutment scour problem, it can be shown that specific groups of dimensionless parameters exist that define different aspects of the physics of the problem. These parameter groups are given as G1.
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6 encompassed both solid abutments and erodible abutments. While no formula was found to satisfy all criteria, the framework developed as a result of this research approach suggests a path toward refining and unifying a small number of leading scour formulas.
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7 patience, the results will move the ultimate solution to the abutment scour problem forward more effectively than less-expensive post-flood surveys. CONCLUSIONS This study leads to the following main conclusions regarding its objectives: 1.
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8 3. The evaluation (Chapter 5)
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