Effect of Debris on Piers Group Scour: An Experimental Study

Rahimi, Ebrahim; Qaderi, Kourosh; Rahimpour, Majid; Ahmadi, Mohammad Mehdi

doi:10.1007/s12205-017-2002-y

Cited by 18 publications

(15 citation statements)

References 15 publications

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“…In this regard, it is expected that the longer the debris is, the smaller the scour hole under it will be. This bed protecting effect of debris is similar to findings by Ebrahimi et al (2018), Rahimi et al (2018) and Dias et al (2019). Therefore, it is assumed that variation of with Ld/D for on-bed debris is as shown in Fig.…”

Section: ( )supporting

confidence: 82%

“…For debris with triangular profile, it was found by Ebrahimi et al (2018) that scour depth is 84% of non-triangular profile debris with the same thickness. Rahimi et al (2018) found this ratio to be 74%. Lagasse et al (2010) found that the scour depth for wedge shape debris is 84% of that for rectangular debris with similar thickness.…”

Section: 25mentioning

confidence: 94%

“…Wellwood andFenwick 1990 andDiehl 1997), available experimental results for this type of debris are excluded due to (i) the relatively small number of experiments available and (ii) the distinct effect this debris geometry has on flow pattern, i.e. less severe flow deflection and higher flow shedding around debris, compared to that of rectangular debris (Lagasse et al 2010 andRahimi et al 2018).…”

Section: Data From Flume Experimentsmentioning

confidence: 99%

“…Lagasse et al (2010) found that the scour depth for wedge shape debris is 84% of that for rectangular debris with similar thickness. This is due to less severe deflection of flow toward pier base in triangular debris compared to rectangular debris (Lagasse et al 2010 andRahimi et al 2018). Therefore, when triangular debris is encountered, the maximum scour depth can be evaluated by using the maximum thickness of the debris within the proposed method for computing , and the resulting value multiplied by 0.74-0.84 to obtain scour depth for triangular debris.…”

Section: 25mentioning

confidence: 99%

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A method for evaluating local scour depth at bridge piers due to debris accumulation

Ebrahimi

Djordjević

Panici

et al. 2020

Proceedings of the Institution of Civil Engineers - Bridge Engi

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This paper introduces a novel method for evaluating the effect of debris accumulation on local scour depth at bridge piers. The concept of a debris factor is proposed to replace the current effective and equivalent pier width approaches that have been shown to overestimate debris-induced scour in many instances. The concept enables a simpler, more direct and realistic estimation of the change in local scour depth due to debris since it accounts for (i) debris length (streamwise), width (spanwise) and thickness (depth wise), and (ii) the influence of debris elevation in flow, i.e. is applicable for free-surface debris, submerged debris, or debris resting on the stream bed. The concept works with all existing local scour equations alongside other factors that influence scour depth such as flow angle of attack and pier shape. The mathematical model that underpins the proposed concept is derived through multiple linear regression on experimental data obtained at Exeter and elsewhere. The proposed method is shown to improve accuracy by at least 24% and 5% in comparison to the effective and equivalent pier width approaches, respectively. More importantly, the method is shown to be robust, providing highly consistent results with significantly less uncertainty.

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Section: ( )supporting

confidence: 82%

Section: 25mentioning

confidence: 94%

Section: Data From Flume Experimentsmentioning

confidence: 99%

Section: 25mentioning

confidence: 99%

See 2 more Smart Citations

A method for evaluating local scour depth at bridge piers due to debris accumulation

Ebrahimi

Djordjević

Panici

et al. 2020

Proceedings of the Institution of Civil Engineers - Bridge Engi

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“…Pagliara and Carnacina [3] carried out a study to observe the temporal evolution of debris modification factors according to different shapes of debris and proposed a relationships with respect to contraction area by debris up to 13%. The maximum scour depth with debris was observed when the rectangular formation considered at single and pier groups as compared with other geometries of debris, Further, debris can reduce the scour depth when and act just as collar at relative submerged depth of 0.46 [4]. Pagliara and Carnacina [5] performed an experimental study to evaluate the change in the velocity and turbulence patterns when debris accumulated around a pier.…”

Section: Introductionmentioning

confidence: 99%

Empirical Formulas to Predict the Maximum Scour Depth With Debris Accumulation Around A Single Cylindrical Bridge Pier: An Experimental Study

Al-Khafaji

Al-Awadi²

2020

ETJ

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The probability of debris accumulation near bridge piers during the heavy storm and river flood convert the ‎hydraulic action of flow and increase the scour depth due to the reduction of flow area and the increase in ‎velocity of flow. In this paper, the effects of debris accumulation length, width and submerged depth on ‎scour depth near bridge pier were investigated. An experimental study for three groups of woody debris ‎accumulation was conducted under clear water condition to investigate the effects on maximum scour depth. ‎The results showed that the increase of blocked area of debris ‎to 27% increases the scour depth by approximately 140%. Furthermore, two empirical exponential formulas was proposed to predict the effect of ‎debris on the maximum scour depth and the modification factor required for single pier. Well agreement ‎was obtained for both derived formulas with coefficient of determination (R2) of 0.96. ‎

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