Six legged concrete (SLC) elements as scour countermeasures at wing wall bridge abutments

Zolghadr, Masih; Bejestan, Mahmood Shafai

doi:10.1080/15715124.2020.1726357

Cited by 10 publications

(9 citation statements)

References 17 publications

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“…However, since the current study aims to compare how different arrangements of the countermeasures affect abutment scour reduction, the duration used in the study was shortened. Similar studies with shorter experiments dealing with scouring can be found in the literature with 4 h duration or less [16,52].…”

Section: Laboratory Experimentssupporting

confidence: 83%

“…The former includes installing heavy elements such as riprap stones, gabions, cable-tied blocks, reno-mattresses, grout bags, etc. Flow-altering countermeasures, however, include the installation of submerged vanes, collars, sacrificial piles, spur dikes, and slots [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…From a scouring perspective, riprap stones should be designed to withstand the local shear stresses that form at the abutment. According to Chiew [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]; and Melville et al [20], riprap layer failures around bridge foundations include shear, winnowing, edge and bed-form undermining failures. Shear failure, which occurs when turbulent flow erodes and moves riprap stones around bridge foundations, can be mitigated by using an appropriate riprap size.…”

Section: Introductionmentioning

confidence: 99%

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Combination of Riprap and Submerged Vane as an Abutment Scour Countermeasure

Fathi

Zomorodian

Zolghadr

et al. 2023

Fluids

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Scour is one of the main causes of hydraulic structural failures. The present experimental study examines the use of riprap, submerged vanes, and a combination of these for scour reduction around vertical walls and spill-through abutments under clear-water conditions. Specifically, the influence of placing riprap stones with different apron shapes (geometry) and/or a group of submerged vanes of constant height and length on abutment scour was examined. The main aim is to propose the optimum apron geometry and placement of submerged vanes to (1) reduce edge failure at vertical walls and spill-through abutments; and (2) prevent shear failure at the spill-through abutment (no shear failure is observed around the vertical wall abutment). The results show that using ripraps for scour protection is more effective than submerged vanes. However, the highest reduction in scour depth was achieved when a combination of riprap and submerged vanes was used together. This arrangement can reduce the maximum clear-water scour depth by up to 54% and 39% with vertical walls and spill-through abutments, respectively. Furthermore, selecting appropriate apron scale ratios reduces the required riprap volume by up to 46% and 31% for the vertical wall and spill-through abutment, respectively. In addition, the installation of vanes increased the riprap stability and reduced edge failure in both abutments tested. Finally, using riprap aprons with proper scales ratios at the downstream side of the spill-through abutment also prevents shear failure in this zone.

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Section: Laboratory Experimentssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Combination of Riprap and Submerged Vane as an Abutment Scour Countermeasure

Fathi

Zomorodian

Zolghadr

et al. 2023

Fluids

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“…Eighty-four experiments in total were carried out at range of 0.1,Fr,0.4 (Froude numbers in main channel and upstream of turnout). The depth of water in the main channel in the experiments was 9 cm, in which case the effect of surface tension can be considered; according to research by Zolghadr & Shafai Bejestan (2020) and Zolghadr et al (2021), when the water depth is more than 6 cm, the effect of surface tension is reduced and can be ignored given that the separation phenomenon occurs in the boundary layer, the height of the roughness creates disturbances in growth and development of the boundary layer and, as a result, separation growth is also faced with disruption and its dimensions grow less compared to smooth surfaces. Similar conditions occur in case of drop implementation.…”

Section: Methods Experimental Setupmentioning

confidence: 99%

Experimental and numerical study of flow at a 90 degree lateral turnout with enhanced roughness coefficient and invert level changes

et al. 2022

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Flow separation at the upstream side of the lateral turnouts (intakes) is a critical issue causing eddy currents at the turn-out entrance. It reduces the effective width of flow, turn-out capacity and efficiency. Therefore, it is essential to identify the dimensions of the separation zone and propose remedies to reduce its dimensions. Installation of 7 types of roughening elements at the turn-out entrance and 3 different bed level inverts, with 4 different discharges (total of 84 experiments) were examined in this study as a method to reduce the dimensions of the separation zone. Additionally, a 3-D Computational Fluid Dynamic (CFD) model was utilized to evaluate the flow pattern and dimensions of the separation zone. Results showed that enhancing the roughness coefficient can reduce the separation zone dimensions up to 38% while the drop implementation effect can scale down this area differently based on the roughness coefficient used. Combining both methods can reduce the separation zone dimensions up to 63%.

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“…Zolghadr et al demonstrated that installation of A-Jacks armors could control scouring at the trapezoidal crest up to 100%. Extensive research has been undertaken in Shahid Chamran University in order to examine application of six-legged elements for protecting the stilling basins' bed, indicating that a proper arrangement of these elements could reduce the stilling basin at length and the conjugate depth as well as scour depth downstream of the basins [5,6]. Hosein Reza et al applied the combined method of utilizing both ripraps and six-legged elements as direct methods of controlling scour at a rectangular abutment.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Performance of A‐Jacks Concrete Armor Units in Riverbeds around Downstream in Flip Buckets

Khalifehei

Azizyan

Shafai-Bajestan

2021

Shock and Vibration

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The jet flipped from flip buckets hits the dam’s downstream side as a free jet with an immense amount of energy, leading to bed erosion. Erosion of river bed materials downstream of dams could affect the performance of dams or power plants by altering the tailwater depth, rendering proper designs of controlling structures or erosion reduction methods highly indispensable in this regard. Hence, the hydrodynamic performance of A-Jacks concrete armor units in controlling scour was examined in this study. A-Jacks armors are applicable as a flexible protection without environmental risks often for bed erosion control. The desirable functionality of A-Jacks armors depends on the flow hydrodynamic parameters such as velocity profile variations ( U / U B ), the Reynolds stresses ( τ u ′ w ′ and τ v ′ w ′ ), and the skin friction coefficient ( C f ) created as a consequence of using A-Jacks armors on beds. The size of A-Jacks elements can have a role in increasing the flow turbulence to a certain depth so that after the impact of the flow with A-Jacks armor, the vortices’ intensity as well as the shear stress affecting the bed gradually decreases. The results of the numerical model suggest that the surge in the flow turbulence energy dissipation downstream of flip buckets significantly mitigates the underlying conditions of scouring phenomena, which is evidence of A-Jacks armors’ acceptable performance in scaling down scour depths.

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Six legged concrete (SLC) elements as scour countermeasures at wing wall bridge abutments

Cited by 10 publications

References 17 publications

Combination of Riprap and Submerged Vane as an Abutment Scour Countermeasure

Combination of Riprap and Submerged Vane as an Abutment Scour Countermeasure

Experimental and numerical study of flow at a 90 degree lateral turnout with enhanced roughness coefficient and invert level changes

Hydrodynamic Performance of A‐Jacks Concrete Armor Units in Riverbeds around Downstream in Flip Buckets

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