Effect of Gradation of Bed Material on Local Scour Depth

Mir, Bintul Huda; Lone, M. A.; Bhat, Javed Ahmad; Rather, Nasir Ahmad

doi:10.1007/s10706-018-0479-x

Cited by 11 publications

(5 citation statements)

References 8 publications

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“…However, the effects of changing the sediment beds cannot be addressed by only d 50 in non-uniform sediment mixtures. Also, the grain size distribution of the bed material and, in particular, the volume percent of sand-sized bed particles plays a significant role in the armoring process and the armor layer texture (Curran and Waters, 2014;Mir et al, 2018;Orrú et al, 2016). To incorporate the effects of grain size distribution on the maximum scour depth in non-uniform sediment mixtures, the bed material gradation should be employed.…”

Section: Results and Discussion Data Presentation And Results For Sin...mentioning

confidence: 99%

“…The experimental observations of Okhravi et al (2019) revealed that with increasing the flow rate, the armor layer became coarser, as more and more of the sediment particles are transported by the flow. The recent relevant studies of Mir et al (2018) and Namaee and Sui (2019) on the local pier scour pointed out that scour depth predictors for the cases of realistic field conditions (i.e., river bed) should incorporate at least both sediment gradation (σ g ) and d 50 to predict maximum scour depth with a higher degree of accuracy.…”

Section: Introductionmentioning

confidence: 99%

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Effects of bed-material gradation on clear water scour at single and group of piles

Okhravi

Gohari

Alemi

et al. 2022

Journal of Hydrology and Hydromechanics

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This study presents the results of 32 laboratory experiments on local scour at a single pile and a 1 × 4 pile group for both uniform and non-uniform sediments under clear water conditions. The present study aims to evaluate the effects of different sediment beds made up of mixtures of sand and gravel (four-bed configurations) in d 50 (1–3.5 mm) and gradation (1.4–3) ranges on scour depth for different flow discharges and flow depths. Further, the findings of the experiments are deployed to describe the effects of pile spacing and flow conditions on the local pier scour for both uniform and non-uniform bed granulometries. In addition, this study addresses the performance of some existing scour-depth predictors. Also, the corresponding results are suitable for validating the numerical models in local pier scour prediction importantly with non-uniform sediments. In summary, the results show that effects of sediment gradation dampen with increasing flow shallowness. Furthermore, the maximum scour depth at pile groups generally increases as pile spacing decreases for uniform sediments, whereas the mentioned trend was not observed for non-uniform sediments for the same flow and sediment conditions. Moreover, the experimental results revealed that bed sediment gradation is a controlling factor in the pile’s scour. Thus, the existing scour depth predictions could be highly improved by considering sediment gradation in the predictions. Finally, the conclusions drawn from this study provide crucial evidence for the protection of bridge foundations not only at the front pile but also at rear piles.

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Section: Results and Discussion Data Presentation And Results For Sin...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of bed-material gradation on clear water scour at single and group of piles

Okhravi

Gohari

Alemi

et al. 2022

Journal of Hydrology and Hydromechanics

View full text Add to dashboard Cite

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“…Hoffmans [60] defined σ g < 1.3 as uniform sediment, and stated that sediments non-uniformity σ g was about 1.8 in natural rivers. Researchers found that the scouring rate and scour depth decreased significantly with σ g increased [61][62][63]. Chiew and Melville [62], for an example, observed that the finer particles would be armored by coarse particles both on the upstream bed and at the scour hole.…”

Section: Sedimentsmentioning

confidence: 99%

Local Scour for Vertical Piles in Steady Currents: Review of Mechanisms, Influencing Factors and Empirical Equations

Liang

Pan

et al. 2019

JMSE

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Scour induced by currents is one of the main causes of the bridge failure in rivers. Fundamental knowledge and mechanisms on scour processes due to currents are often taken as a basis for scour studies, which are the focus of this review. Scour development induced by waves and in combined wave–current conditions are also briefly discussed. For the design of structure foundations, the maximum scour depths need to be estimated. The mechanisms of local scour and predictions of maximum local scour depths have been studied extensively for many years. Despite the complexity of the scour process, a lot of satisfying results and progresses have been achieved by many investigators. In order to get a comprehensive review of local scour for vertical piles, major progresses made by researchers are summarized in this review. In particular, maximum scour depth influencing factors including flow intensity, sediments, pile parameters and time are analyzed with experimental data. A few empirical equations referring to temporary scour depth and maximum scour depth were classified with their expressing forms. Finally, conclusions and future research directions are addressed.

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“…Correction of bridge pier shape (K 1) is also called shape factor (K sh ). K sh for the uniform shape of piers i.e., piers having constant section throughout their depth (Melville and Coleman, 2000), have been suggested by several investigators, including Tison (1940), Chabert and Engeldinger (1956), Laursen and Toch (1956), Larras (1963), Venkatadri et al (1965), Dietz (1972), Neill (1973), Richardson and Davis (1995) and Mir et al (2018). The shape factor is defined as the ratio of scour depth measured for a non-circular shape of a pier to the scour depth for a circular shape pier (Talib et al 2016).…”

Section: Variation Of Scour Depth With Velocitymentioning

confidence: 96%

A comparative study of scour around various shaped bridge pier

2023

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The study of scouring around bridge piers is very significant and plays a very important role in the safe and economical design of bridge piers. The term scouring is a process by which bed particles around the periphery of the pier get eroded and removed over a certain depth resulting in the formation of a scour hole around the bridge piers. This paper presents a detailed investigation of local scouring around six different shapes namely rectangular, circular, chamfered, joukowsky, oblong, and sharp-nosed of bridge pier models for selecting the best and most economical bridge pier shapes based on local scouring. For the experimental studies, local scour depth is measured around all six different shapes of bridge piers with varying discharges and velocities of 0.0169 m3/s to 0.0355 m3/s and 0.17 m/s to 0.30 m/s respectively. It is found that scour depth around the rectangular shape of bridge pier is larger due to development of strong intensity of horseshoe vortex caused by flat exposed frontal area and scour depth around the sharp nose shape of the pier is smaller because of flow is bifurcated due to smooth curvature caused less intensity of development of horseshoe vortex. In the comparison of obtained results, it is reported that scour depth around a pier is exactly proportional to velocity of approach flow and exposed frontal area of the bridge pier. The result of this study can be likely used to help in selecting the best shape of the bridge piers as sharp nose shape of bridge piers is better among the other six bridge pier shapes for design purposes. Key Words: Local scour, shape of bridge pier, fine bed material, scour depth

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Effect of Gradation of Bed Material on Local Scour Depth

Cited by 11 publications

References 8 publications

Effects of bed-material gradation on clear water scour at single and group of piles

Effects of bed-material gradation on clear water scour at single and group of piles

Local Scour for Vertical Piles in Steady Currents: Review of Mechanisms, Influencing Factors and Empirical Equations

A comparative study of scour around various shaped bridge pier

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