Application of Riprap and Collar to Prevent Scouring around Rectangular Bridge Piers

Mashahir, Mohammad B.; Zarrati, Amir Reza; Mokallaf, Ebrahim

doi:10.1061/(asce)hy.1943-7900.0000145

Cited by 47 publications

(24 citation statements)

References 9 publications

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“…The last two countermeasures intend to align the upstream flow and minimize the influence of attack angle variation. Numerical methods are applied in some researches to study the effectiveness of riprap (the most common countermeasure) and collars as countermeasures to bridge scour (Negm et al 2009, Mashahir et al 2010. Riprap and collars work as scour countermeasures by stabilizing the critical shear zones near pier footings.…”

Section: Introductionmentioning

confidence: 99%

Streamlining of Bridge Pier as a Scour Countermeasure: A Feasibility Study

Tao

2015

Ifcee 2015

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Scour around bridge pier is known as one of the most critical causes to bridge failure. Countermeasures suggested by HEC-23 (2009) include riprap, gabions, spurs, guide banks, and so on. The principals of these countermeasures are either mechanically stabilizing the channel bed surface to prevent the development of the scour hole, or reducing the vortex intensity. Streamlining of the piers is a potentially feasible countermeasure to bridge scour by reducing the vortex strength. In this paper, Computational Fluid Dynamics (CFD) models are developed to evaluate the feasibility of streamlining as a countermeasure. Five test cases with different streamlining features are systematically analyzed and compared. It is found that the vertical profile of the pier nose and sidewalls has significant effects on the development of vortex structures around piers. Streamlined pier nose and sidewalls help reduce the downward flow in front of the piers, the vortex extent around the pier and the bed shear stress intensity. If the pier is not aligned with the incoming flow, however, the effectiveness of streamlining as a scour countermeasure may be highly compromised.

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Section: Introductionmentioning

confidence: 99%

Streamlining of Bridge Pier as a Scour Countermeasure: A Feasibility Study

Tao

2015

Ifcee 2015

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“…8a). Combining a collar and a riprap, Mashahir et al (2010) proposed a configuration in which the sediment around the collar should be protected with a riprap (Tafarojnoruz and Gaudio 2011). Increasing the bed-sill thickness, these zones were part of the non-erodible bed sill or were protected by a border (Fig.…”

Section: Combination Of a Bed Sill And A Collarmentioning

confidence: 99%

“…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. Mashahir et al (2010) studied the size and extent of a riprap around rectangular piers protected with a collar.…”

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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“…Collars have also been employed in combination with other methods Kumar et al 1999;Mashahir et al 2010;Zarrati et al 2006). Moncada-M et al (2009) demonstrated the effects produced by a collar with a rectangular slot around a circular pier controlled the scour depth.…”

Section: Introductionmentioning

confidence: 99%

Experimental study for determination of collar dimensions around bridge pier

Jahangirzadeh

Akib

2015

The Baltic Journal of Road and Bridge Engineering

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The shape and size of a collar is important to maximize its effect as a scour countermeasure. Current research shows that the depth of the scour hole is decreased by using rectangular collars around circular piers. This study determined the approximate optimum dimensions for rectangular collars to minimize the temporal trend of scouring around a pier model. Effects of different sizes of rectangular collars on a model pier were investigated both at the upstream and downstream of the flume. It was observed that irrespective of the rectangular collar dimensions the upstream and the downstream were estimated to be 0.86 and 1.42, respectively. The optimum collar width was estimated to be 2.8 times the diameter of the pier. By using this optimized collar dimension, the non-dimensional depth of scour reached a min value of 0.034 at 72 h. The reduction percentage of the scour depth reached 98% at 72 h.

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Application of Riprap and Collar to Prevent Scouring around Rectangular Bridge Piers

Cited by 47 publications

References 9 publications

Streamlining of Bridge Pier as a Scour Countermeasure: A Feasibility Study

Streamlining of Bridge Pier as a Scour Countermeasure: A Feasibility Study

Combined flow-altering countermeasures against bridge pier scour

Experimental study for determination of collar dimensions around bridge pier

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