Reduction of Local Scour in the Vicinity of Bridge Pier Groups Using Collars and Riprap

Zarrati, Amir Reza; Nazariha, M.; Mashahir, Mohammad B.

doi:10.1061/(asce)0733-9429(2006)132:2(154)

Cited by 103 publications

(50 citation statements)

References 14 publications

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“…The objective of those works was an estimation of maximum scour depth around pile groups for safe and economic designs. In addition to the estimation of scour depth, some studies deal with proposing scour countermeasures at pier groups [14,15]. Thus, some semi-empirical equations for maximum scour depth have been proposed [10,11,13].…”

Section: Introductionmentioning

confidence: 99%

Computational Modeling of Flow and Scour around Two Cylinders in Staggered Array

Kim

Roh

Nabi

2017

Water

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This paper presents a numerical study on flow and local scour around two identical cylinders with diverse spacing ratios (s/D) and alignment angles (α). The spacing ratio of center-to-center distance between cylinders (s) to the cylinder diameter (D) varied from 1.25 to 5.0, including five alignment angles ranged from 0 • to 90 • . The detailed scour processes and information were obtained in a physics-based way by using large eddy simulation coupled with sediment transport in a Lagrangian framework and a morphodynamic model. Turbulent flow properties around two cylinders in staggered array are significantly concerned by the spacing ratio and the alignment angle which reflect complex features of evolution of scour and scour depth. The computed results exhibited the scour depth is associated with the spacing ratio and alignment angles especially at the rear cylinder. For small alignment angles, the growth rate at the rear cylinder increased as the spacing ratio increased, due to a decrease in shielding effect. As the alignment angle increased, the scour depth around the rear cylinder increased until the angle reached approximately 45 • -60 • . Subsequently, the scour depth decreased with the alignment angle. It also revealed that the spacing ratio was more sensitive to the maximum scour than that of the alignment angle. For (s-D)/D > 2.0, the maximum scour depth only depended on the spacing ratio.

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Section: Introductionmentioning

confidence: 99%

Computational Modeling of Flow and Scour around Two Cylinders in Staggered Array

Kim

Roh

Nabi

2017

Water

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“…These vortices are unstable and shed disorderly from each side of the pier. They act as little tornadoes lifting the sediment from the bed to form a scour hole downstream of the pier (Zarrati et al 2006;Heidarpour et al 2010).…”

Section: Introductionmentioning

confidence: 99%

RETRACTED ARTICLE: Adaptive neuro-fuzzy estimation of the influence of slot on local scour at bridge pier groups

et al. 2014

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Scouring around bridge pier is a major cause of bridge instability. Thus, providing appropriate methods in order to reduce and control the scour depth have received much attention. Using a slot in the bridge piers is one of modern methods of reducing bridge local scouring. In the present study, the effects of a rectangular slot on local scour mitigation around bridge pier groups have been investigated with adaptive neurofuzzy (ANFIS) method. ANFIS shows very good learning and prediction capabilities, which makes it an efficient tool to deal with encountered uncertainties in any system like scouring. The results show that the scour depth increased in the first pier by reinforcing effect and it decreased in the rear piers because of sheltering effect in compare with single pier. In addition, application of the slot in pier groups leads to an increase in the impact of reinforcing effect and reduce the influence of sheltering effect.The use of slot is more influential in front bridge piers than the rear piers in pier groups with 4D distance, however, this effectiveness doesn't have significant difference among the piers with 2D distance and same as single pier. Laboratory experiments were conducted to create experimental training and checking data for ANFIS network. This intelligent estimator is implemented using Matlab/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method.

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“…Based on these results, a slot combined with a collar should not be sunk under the initial bed level because scour intrusion beneath the collar is expected if a portion of the collar rim is exposed to the flow during bed-form passage or as degradation occurs. According to Zarrati et al (2006), the scour initiates at the rear of a pier protected with a 3b-wide collar placed at the initial bed level, owing to the wake vortex system action. In the combination of a pier slot and a collar, the slot outflow may affect the structure of wake vortices and deviate them downstream.…”

Section: Combination Of a Slot And A Collarmentioning

confidence: 99%

“…Parker et al (1998) combined permeable sheet piles with a riprap under live-bed conditions, noting a scour depth reduction of up to 91%. Zarrati et al (2006) covered the space inside the continuous collar and between two in-line piers with a riprap layer to prevent rapid scour development between them. Grimaldi et al (2009b) protected a circular pier with a downstream bed sill combined with a slot under clear-water conditions by employing uniform sand, obtaining an average efficiency of 45% in the best configurations.…”

Section: Introductionmentioning

confidence: 99%

Combined flow-altering countermeasures against bridge pier scour

Gaudio

Tafarojnoruz

Calomino

2012

Journal of Hydraulic Research

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This study presents the results of clear-water tests on the following five combined flow-altering countermeasures against bridge pier scour: (1) submerged vanes and a bed sill, (2) slot and sacrificial piles, (3) a collar and sacrificial piles, (4) a slot and a collar, and (5) a bed sill and a collar. Each countermeasure was designed on the basis of the best configuration recommended in the literature. The results clarify that an improper combination of two countermeasures may be less effective than each individual countermeasure; combinations (1), (2), and (3) do not reduce the scour depth significantly with respect to the single countermeasures; combination (3) increases the scour rate during the first few hours with respect to a single collar; combination (4) may also prevent scour intrusion beneath a collar; and combination (5) in the best configuration reduces the scour depth significantly around the collar with respect to maximum scour depth of the unprotected pier, preventing also the scour hole reaching the pier body.

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Reduction of Local Scour in the Vicinity of Bridge Pier Groups Using Collars and Riprap

Cited by 103 publications

References 14 publications

Computational Modeling of Flow and Scour around Two Cylinders in Staggered Array

Computational Modeling of Flow and Scour around Two Cylinders in Staggered Array

RETRACTED ARTICLE: Adaptive neuro-fuzzy estimation of the influence of slot on local scour at bridge pier groups

Combined flow-altering countermeasures against bridge pier scour

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