Developing empirical formulas for assessing the scour of vertical and inclined piers

Omara, Hamdy A.; Abdeelaal, G. M.; Nadaoka, Kazuo; Tawfik, Ahmed

doi:10.1080/1064119x.2018.1559901

Cited by 11 publications

(3 citation statements)

References 17 publications

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“…Pandey et al [18], developed a scour equation by employing a multiple linear regression (MLR) model that was optimized with the genetic algorithm. Omara et al [19], have proposed local scour formulas for different flow attack angles on inclined and vertical circular piers.…”

Section: Introductionmentioning

confidence: 99%

New Formula for Calculating Local Scour around Bridge Piers

Annad

Lefkir

2022

AEF

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Several researchers working on the axes of solid particle transport, river flow, as well as the vulnerability of structures built on rivers have focused their work on the phenomenon of local scour, where many scour formulas have been proposed. Most of these formulas have been developed using laboratory data, estimated from simplified scaled-down models. This led to uncertainties and considerable inaccuracies in the scour estimation, sometimes causing serious consequences for the stability of structures subject to scour. These formulas were rarely tested using field data, where, until recently, there was very little data to validate them. This study aims to propose a new local scour formula using multiple nonlinear regression (MNLR). The data used is in situ data from an extensive database. The new proposed formula includes different parameters of the three fields involved in the triggering and development of the local scour, namely; the bridge, the flow, and the suspended characteristic of the eroded particle. The results obtained in the training phase and the validation show relatively better performances of the new formula compared to the existing empirical formulas.

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Section: Introductionmentioning

confidence: 99%

New Formula for Calculating Local Scour around Bridge Piers

Annad

Lefkir

2022

AEF

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“…To generate the data, an experimental study is established for the establishment of the formula, data collected from other studies are also exploited. (Omara et al 2020) proposed several scour formulas under shallow flow conditions including the effects of the flow intensity, inclination angle (at different angles of flow attack on circular piers), and pier length.…”

Section: Introductionmentioning

confidence: 99%

Development of a local scour prediction model clustered by soil class

Annad

Lefkir

Mammar-kouadri

et al. 2021

Water Practice and Technology

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Several studies have been conducted to assess local scour formulas in order to select the most appropriate one. Confronted to the limits of the previous formulas, further studies have been performed to propose new local scour formulas. Generalizing a single scour formula, for all soil classes, seems approximate for such a complex phenomenon depending on several parameters and may eventually lead to considerable uncertainties in scour estimation. This study aims to propose several new scour formulas for different granulometric classes of the streambed by exploiting a large field database. The new scour formulas are based on multiple non-linear regression (MNLR) models. Supervised learning is used as an optimization tool to solve the hyper-parameters of each new equation by using the ‘Gradient Descent Algorithm’. The results show that the new formulas proposed in this study perform better than some other empirical formulas chosen for comparison. The results are presented as seven new formulas, as well as abacuses for the calculation of local scour by soil classes.

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“…Karimi et al [14], examined four inclination piers with downstream side (ϴ = 0°, 5°, 10° and 15°) and their effects on scour hole dimensions for sand bed material of d50 = 1.46 mm with varied flow rates (12 to 18 l/s), they concluded that the maximum scour depth occurs with piers angle (ϴ = 0°), while the minimum depth of scour occurs at ϴ = 15°. Omara et al [15], conducted extensive experimental study for investigating the inclination effect of different piers geometry (square, rectangular and circular) on dimension less scour depth (ds/D) for two bed materials (d50=0.6 and 0.81 mm). The study included the effect of flow depth (0.048 m to 0.08 m), and flow intensity (V/VC from 0.6 to 1.06) beside four inclination angles (ϴ = 10°, 15°, 21° and 30°).…”

Section: Introductionmentioning

confidence: 99%

The Variation of Scour Depth near Vertical and Inclined Cylindrical Bridge Piers: An Experimental Study

Al-Awadi¹

2021

MMEP

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The stability of bridge piers against scouring phenomena require to estimate the scour depth carefully at different hydraulic condition to ensure safe design. In this study, laboratory experiments were carried out to examine and compare the scour depth for vertical and inclined cylindrical piers with downstream direction under clear water scour conditions. The measured scour depth in front of three inclined configurations (ϴ = 10°, 16° and 22°) for single cylindrical pier was compared to that observed at vertical cylindrical pier (ϴ = 0°). The experiments were conducted at four flow intensities (V/VC=0.495, 0.714, 0.824 and 0.989) for sand bed material of d50=0.72 mm. The obtained results revealed and confirmed the inverse relationship between the measured scour depth and the angle of inclination of pier, whereas the maximum and the minimum scour depth was observed at ϴ = 0°, and ϴ = 22° respectively. The results of this study showed that the scour depth near threshold conditions (V/VC=0.989) can be reduced approximately by (5%, 10%, and 15%) for inclined piers with (ϴ = 10°, 16° and 22°) respectively. Furthermore, by assessment of five existing formulas, new modified empirical formula has been proposed for scour depth estimation of inclined piers with ± 9% error margins.

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Developing empirical formulas for assessing the scour of vertical and inclined piers

Cited by 11 publications

References 17 publications

New Formula for Calculating Local Scour around Bridge Piers

New Formula for Calculating Local Scour around Bridge Piers

Development of a local scour prediction model clustered by soil class

The Variation of Scour Depth near Vertical and Inclined Cylindrical Bridge Piers: An Experimental Study

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