Abstract
An experimental approach was conducted to study the effect of the change in the position of bridge pier on scour reduction with respect to flow direction. The experiments included the study of new method to reduce scour depth in front of bridge pier by changing the position of bridge pier (named after here as downstream facing round-nosed bridge pier). The down flow deflected away from the front of the opposite pier, and the vortex becomes small and does not affect the pier. In this study, three piers—circular 10 cm, upstream facing round-nosed (10–4) cm and downstream facing round-nosed (4–10) cm bridge piers—were tested under live-bed condition with flow intensity of 58 l/s for duration of 3 h. The velocity field measurements were obtained using an Acoustic Doppler Velocimeter. The results showed that the downstream facing round-nosed pier reduces local scour. The reduction in maximum scour depth was 54 % when compared to the circular pier and 40 % compared with upstream facing round-nosed pier. The downstream facing round-nosed pier reduces local scour by a volume of 83 % when compared to the circular pier. Changing the position of bridge pier (as is located downstream facing to the flow) is an effective countermeasure for reducing local scour depth. Empirical relationship was developed on the basis of obtained results. The present experimental study shows that there is no need of any alteration or modification to countermeasure scour like riprap, collar and slot. The present method also reduces costs and improves the hydraulic performance of bridge pier.
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Abbreviations
- b :
-
Pier width (m)
- v :
-
Flow velocity (m/s)
- \({\rm {\rho}}\) :
-
Density of fluid (kg/m3)
- h :
-
Flow depth (m)
- g :
-
Gravitational acceleration (m/s2)
- d 50 :
-
Median particle size (mm)
- k s :
-
Shape factor= \({\frac{D_{u/s} }{Dd/s}}\)
- D u/s :
-
Upstream diameter of pier (m)
- D d/s :
-
Downstream diameter of pier (m)
- D :
-
Pier diameter (m)
- Fr :
-
Froude number = \({\left[\frac{v}{\sqrt{gh}} \right]}\)
- F D50 :
-
Densimetric Froude number
- R :
-
Correlation coefficient
- d 16 :
-
Grain size for which 16 % by weight of the sediment is finer
- d 84 :
-
Grain size for which 84 % by weight of the sediment is finer
- \({\partial g= ({d}_{84} /{d}_{16})^{0.5}}\) :
-
Geometric standard deviation of the grain size distribution
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Ismael, A., Gunal, M. & Hussein, H. Effect of Bridge Pier Position on Scour Reduction According to Flow Direction. Arab J Sci Eng 40, 1579–1590 (2015). https://doi.org/10.1007/s13369-015-1625-x
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DOI: https://doi.org/10.1007/s13369-015-1625-x