Influence of Wood Debris Accumulation on Bridge Pier Scour

Pagliara, Stefano; Carnacina, Iacopo

doi:10.1061/(asce)hy.1943-7900.0000289

Cited by 59 publications

(55 citation statements)

References 19 publications

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“…Flow shallowness, h=D 0 , was 1.6 and 2.6 for the two flow depths, corresponding to shallow flow conditions (Chiew 1992;Melville and Chiew 1999). The value h=D 0 ¼ 1.6 was the smallest feasible value that could be attained under the experimental constraints; h=D 0 ¼ 2.6 was smaller than the flow shallowness used in most of the previous research (Lagasse et al 2010;Pagliara and Carnacina 2011b).…”

Section: Hydraulic Conditions Of Experimentsmentioning

confidence: 77%

“…Based on the scour depths in Scenarios 1, 2, and 9, and data from Melville and Dongol (1992), Lagasse et al (2010), and Pagliara and Carnacina (2011b) an attempt is made to characterize the influence of debris thickness T d on scour depth. Data from each of the four sources that have identical hydraulic conditions and debris characteristics excluding T d are grouped together.…”

Section: Effect Of Debris Thicknessmentioning

confidence: 99%

“…8. Two exponential curves were fitted to data; d s =d s;0 ¼ 1 þ 3.2ðT d =hÞ 1.237 for data from Pagliara and Carnacina (2011b) and d s =d s;0 ¼ 1 þ 0.32ðT d =hÞ 1.237 for the rest of data. Fig.…”

Section: Effect Of Debris Thicknessmentioning

confidence: 99%

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Experimental Study on Scour at a Sharp-Nose Bridge Pier with Debris Blockage

et al. 2018

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Previous experimental research on the effects of debris on pier scour has focused primarily on circular and rectangular piers with debris present just under flow free surface. Debris-induced scour around sharp-nose piers, which are typical of masonry bridge piers, and the effect of debris elevation on pier scour have seldom been studied before. This paper aims to fill this knowledge gap. It presents results from flume experiments investigating scour around a sharp-nose pier under shallow flow conditions with angle of attack relative to the pier being zero. Uniform sand is used as bed material. Debris is modeled as stationary and extending only upstream of the pier. Three simplified debris geometries (cylinder, half-pyramid, and plate) are studied. Results show that scour depth decreases as debris gets closer to the bed with maximum scour depth occurring when debris is located just under the flow free surface. Interestingly, scour depths produced by debris in shallow flow are observed to be comparable to those produced by deep flow in the absence of debris. This finding highlights the importance of monitoring debris accumulation at bridges in nonflood conditions. Results also show that the volume of the scour hole around a pier increases quadratically with maximum scour depth. This information is useful for postflood scour remedial works. Lastly, the collected laboratory measurements are used to compare four popular equations for scour estimation on their ability to predict debris-induced scour. The Colorado State University (CSU) equation is found to offer the most accurate predictions. ; separate discussions must be submitted for individual papers. This paper is part of the Journal of Hydraulic Engineering, © ASCE, ISSN 0733-9429. © ASCE 04018071-1 J. Hydraul. Eng. J. Hydraul. Eng., 2018, 144(12): 04018071 Downloaded from ascelibrary.org by 44.224.250.200 on 07/05/20. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04018071-2 J. Hydraul. Eng. J. Hydraul. Eng., 2018, 144(12): 04018071 Downloaded from ascelibrary.org by 44.224.250.200 on 07/05/20. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04018071-5 J. Hydraul. Eng. J. Hydraul. Eng., 2018, 144(12): 04018071 Downloaded from ascelibrary.org by 44.224.250.200 on 07/05/20. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04018071-6 J. Hydraul. Eng. J. Hydraul. Eng., 2018, 144(12): 04018071 Downloaded from ascelibrary.org by 44.224.250.200 on 07/05/20. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04018071-8 J. Hydraul. Eng. J. Hydraul. Eng., 2018, 144(12): 04018071 Downloaded from ascelibrary.org by 44.224.250.200 on 07/05/20. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04018071-10 J. Hydraul. Eng. J. Hydraul. Eng., 2018, 144(12): 04018071 Downloaded from ascelibrary.org by 44.224.250.200 on 07/05/20. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04018071-12 J. Hydraul. Eng.

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Section: Hydraulic Conditions Of Experimentsmentioning

confidence: 77%

Section: Effect Of Debris Thicknessmentioning

confidence: 99%

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Experimental Study on Scour at a Sharp-Nose Bridge Pier with Debris Blockage

et al. 2018

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“…Further, we tested different large woody debris accumulations (Figure d). Large woody debris accumulations at the bridge crossing exert an important forcing acting over the bridge deck and can increase the scour depth at the pier base and the likelihood of bridge failure (Pagliara & Carnacina, ). Reference tests without the pier (only the deck) were also executed.…”

Section: Methodsmentioning

confidence: 99%

Bridge pier scour under pressure flow conditions

Carnacina

Pagliara

Leonardi

2019

River Research & Apps

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The probability of pressurized flow conditions occurring in existing bridges is forecast to increase due to possible changes in extreme precipitation, storm surges, and flooding predicted under climate change scenarios. The presence of a pressure flow is generally associated with scouring processes in proximity to the bridge. Scouring can also occur around bridge piers, possibly causing infrastructure failure. Although there is a vast literature on bridge pier scour and pressure flow scour, only a few studies have investigated their combined effect. This study will provide a new overview of the main features of bridge pier scour under pressurized flow conditions, based on laboratory experiences. Special focus is placed on the analysis of the flow features under pressure and free surface conditions and to the temporal evolution of the scour. A comparison with existing literature data is also conducted. The results highlight the nonlinear nature of scour processes and the need to consider pressurized flow conditions during structural design, as the interaction between pressure flow and the bridge pier strongly influences scour features and leads to scour depths much greater than the sum of the individual scours created only by pressure flow or pier presence.

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“…T* (¼ Uht/A tb ) is the non-dimensional time parameter in the presence of debris accumulation, in which t is time and A tb (¼ Dh + (d d À D)t d ) is the total flow area blocked by the bridge pier and debris accumulation (Pagliara and Carnacina, 2011).…”

Section: Scour Depth Evolutionmentioning

confidence: 99%

Scour control at bridge piers using macro-roughness elements

Pagliara¹,

Palermo²,

Azizi³

2015

Proceedings of the Institution of Civil Engineers - Water Manag

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A new approach involving macro-roughness elements is proposed as a scour countermeasure at circular bridge piers subject to debris accumulation. Experiments were carried out under clear water conditions with the approaching flow velocity set at the threshold of sediment motion. The efficiency of the method was investigated in terms of scour morphology reduction and temporal scour evolution. The results show the effectiveness of the method in reducing maximum scour depth. In some cases, the elements did not reduce the maximum scour depth but were effective in reducing the volume of the scour hole. Based on the experimental data, empirical equations were derived to estimate the temporal local scour depth in the presence of debris accumulation and macro-roughness elements

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Influence of Wood Debris Accumulation on Bridge Pier Scour

Cited by 59 publications

References 19 publications

Experimental Study on Scour at a Sharp-Nose Bridge Pier with Debris Blockage

Experimental Study on Scour at a Sharp-Nose Bridge Pier with Debris Blockage

Bridge pier scour under pressure flow conditions

Scour control at bridge piers using macro-roughness elements

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