Bridge abutment-induced sediment scour in compound river channels is time-sensitive during floods,and,thus,estimating the scour rate has significance in design.In the current study,large-scale laboratory experiments were done to examine the influence of multiple factors on scour evolution,including channel geometry,bed mobility(clear-water or live-bed),and lateral(embankment intrusion)and vertical(deck submergence)flow contractions.A new method is applied for scour measurement and determination of characteristic scour trends.Results show that the non-dimensional time scale is related to flow intensity and may peak before reaching the clear-water scour threshold;the corresponding equations also are derived.It is found that the use of scour countermeasures has a significant impact on the scour rate,and the existing equations for unpro-tected abutments have limitations.Under clear-water conditions,the scour rate is closely related to the overall flow contraction,which can be better reflected by the ratio of the approaching unit discharge to that at the bridge section.Specifically,the effect of vertical flow contraction on scour rate is more dominant than other factors.Two scour rate curves are derived to suit different struc-tural and flow contraction types for clear-water scour.In contrast,the live-bed scour rate data are generally consistent and fall in a narrow band,showing less dependence on other factors.Finally,a new design approach is established to estimate the time scale and scour rate using the new equations proposed in this paper.

Yifan Yang;Bruce W.Melville;Xiaozhou Xiong;Lu Wang

School of Engineering,The University of Waikato,Hamilton,New Zealand;Department of Civil and Environmental Engineering,The University of Auckland,Auckland,New Zealand;Risland New Zealand,Auckland,New Zealand;State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resource and Hydropower,Sichuan University,Chengdu,China

国际泥沙研究（英文版）

[1]Yifan Yang;Bruce W.Melville;Xiaozhou Xiong;Lu Wang-.Temporal evolution of scour at bridge abutments in compound channels)[J].国际泥沙研究（英文版）,2022(05):662-674

abutments,abutment,unpro

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