Performance of the Roughness Elements Distances to Reduce Scour and Their Impact on Vertical Velocity Profiles around Bridge Abutment

Authors

1 M.Sc. Department of Water Engineering, Agricultural College, Isfahan University of Technology, Isfahan, Iran

2 Prof. Department of Water Engineering, Agricultural College, Isfahan University of Technology, Isfahan, Iran

3 Instructor Water Engineering Department, Agricultural College, Isfahan University of Technology, Isfahan, Iran

Abstract

Among the issues related to bridges distraction, a flood which causes scouring has been known as the main reason of bridges destruction. Therefore, finding an effective solution is vital for decreasing scouring depth. In this study, the effects of local roughness elements with different distance were investigated for a semicircular abutment under clear water scouring condition. Results showed that existence of roughness reduced the scouring process and reduced the final scour depth by 47%. There was a significant relationship between roughnesses function and the distance between them. So that the existence of an optimal value for the distance between the roughnesses increased the roughness function and decreased the scouring process. In addition, the study of vertical velocity profiles revealed that existence of positive vertical velocity in the hole located at upstream of the abutment and also negative velocities at higher depths were the indicator of downflows. As a result, these downflows lead to the formation of powerful vortexes inside the scouring hole and in front of the abutment. Comparison of the flow profile around the roughened abutment with the control abutment showed that velocity of downflow is significantly reduced for abutment with roughness. Moreover, the depth of scouring hole was reduced at behind of the abutment, due to the impact of roughness on vertical velocity profiles at downstream of abutment. So that, the velocity reduction of the vertical flow in the front and behind of the roughened abutment was to 0.13 U and 0.4 U (U approaching flow velocity), respectively.

Keywords

References

Afzalimehr H, Bakhshi S, Gallichand J and Sui J, 2014. Effect of vegetaded-banks on local scour around a wing-wall abutment with circular edges. Journal of Hydrodynamics 26(3): 447-457.
Alizadeh VN, Saneie M, and Azhdary Moghaddam, M, 2012. Experimental investigations on effect of buried vane’ angels to control scour at vertical wall abutments and spur dykes. 9th International Congrees on civil engineering. Isfahan.
Barbhuiya AK and  Dey S, 2004. Velocity and turbulence at a wing-wall abutment. Sadhana, Academy Proceedings in Engineering Sciences 29(1): 35-56.
Barbhuiya AK and Dey S, 2003. Vortex flow field in a scour hole around abutments. Sediment Research 18(4): 310-325.
Champour M and Kashefipour S, 2016. Laboratory investigation on the effect of permeable spur dike length on scour hole dimensions in a mild 90 degrees bend under non-submerged conditions. Water and Soil Science - University of Tabriz 26(2-2): 163-175. (In Farsi)
Dey S and Barbhuiya AK, 2005b. Turbulent flow field in a scour hole at a semicircular abutment. Canadian Journal of Civil Engineering 32(1): 213-232.
Dey S and Barbhuiya AK., 2005a. Flow field at a vertical-wall abutment. Journal of Hydraulic Engineering 131(12):1126-1135.
Dey S and Raikar RV, 2007. Characteristics of horseshoe vortex in developing scour holes at piers. Journal of Hydraulic Engineering 133(4): 399-413.
Graf  WH and Istiarto I, 2002. Flow pattern in the scour hole around a cylinder. Journal of Hydraulic Research 40(1): 13-20.
Hong SH, Sturm TW and Stoesser T, 2015. Clear water abutment scour in a compound channel for extreme hydrologic events. Journal of Hydraulic Engineering 141(6): 04015005.‏
Karami H, Ardeshir A, Saneie M and Salamatian SA, 2012. Prediction of time variation of scour depth around spur dikes using neural networks. Journal of Hydroinformatics 14(1):180-191.
Koken M, and Constantinescu G, 2014. Flow and turbulence structure around abutments with sloped sidewalls. Journal of Hydraulic Engineering 140(7): 04014031.‏
Kumar V, Raju KGR and Vittal N, 1999. Reduction of local scour around bridge piers using slots and collars. Journal of Hydraulic Engineering 125(12): 1302-1305.
Melville B, 1992. Local scour at bridge abutments. Journal of Hydraulic Engineering 118: 615-631.
Parchami L, Asghari Pari S and Shafai Bajestan M, 2017. experimental investigation of submerged vanes shape effect on bridge pier scouring. Water and Soil Science- University of Tabriz 27(1): 29-41. (In Farsi)
Raudkivi AJ and R Ettema, 1983. clear-water scour at cylindrical piers. Journal of Hydraulic Engineering 109(3): 338-350.
Saker MA, 1998. Flow measurement around scored bridge piers using Acoustic Doppler Velocimeter (ADV). Flow Measurement and Instrumentation 9:217-227.
Shahsavari H,  Heidarpour M and  Rahiminia A, 2015. Investigation velocity profiles in three directions x, y, z around a semi-circular abutment. 13th National Conference on Irrigation and Evaporation Reduction, Kerman, Shahid Bahonar University of Kerman. (In Farsi)
Shahsavari H and Heidarpour M, 2014. Investigation the effects of the size and the level of collar on semi-circular abutment scouring. National Conference on Civil Engineering, Urban Development and Sustainable Development, Tehran, Center for Sustainable Development of Science and Technology Farzin, Shahid Beheshti University. (In Farsi)
Water and Soil Science
Volume 29, Issue 1
April 2019
Pages 53-67

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