Comparison of Bridge Piers Shapes According to Local Scour Countermeasures

Year 2019, Volume: 6 , 171 - 180, 25.07.2019

Abdulnaser Kashmoola Adnan Ismael Saleh Suleıman

Abstract

Comparison
of experimental study was carried out between bridge piers to find out the efficient
bridge pier to countermeasures the local scour. In addition the present study
is to provide a new method to reduce scour depth in front of bridge pier .The
idea of this method is dependent on change the position of two piers (normal
pier (10-4) cm and straight aero foil shaped pier) with respect to flow
direction (named after here as opposite bridge pier and opposite aero foil
pier). The down flow deflected away from the front the opposite piers and the
horseshoe vortex becomes small and does not affect the piers.In the present
study five piers (normal pier (10-4), opposite pier (4-10), straight aero foil,
opposite aero foil and circular) were tested under live-bed condition with flow
intensity 58 l/sec. for duration 3 hrs. The velocity field measurements were
obtained using an Acoustic Doppler Velocimeter. The results showed that the
opposite piers reduce the local scour around the piers. For opposite pier the
reduction of scour depth was about 40% compared with normal pier and 54%
compared with circular pier. The reduction of the scour hole volume was about
83% compared with circular pier and 23.6% when normal pier compared with
circular. For opposite aero foil the maximum depth of scour reduced 58%
compared with straight aero foil and 69% compared with circular pier. The
reduction of the scour hole volume was about 89% compared with circular pier
and straight aero foil reduced scour hole volume about 27% when compared with
circular pier.It is clearly from the comparison that the opposite piers are effective
countermeasures for reducing local scour depth and scour hole volume,
especially opposite aero foil pier. We hope that the results of the present
study will be benefitted by the designers and engineers.

Keywords

Bridge pier position , Scour reduction , Local scour , Aero foil pier

References

• T. M. Muzzammil, Gangadharaiah and A.K. Gupta. (2004)"An experimental investigation of a horseshoe vortex induced by a bridge pier." Water Manage. 157: 109-119. Tafarojnoruz et al. (2012). “Evaluation of Flow-Altering Countermeasures against Bridge Pier Scour” Journal of. Hydraulic. Eng.138:297-305. Chen et al. (2012). Experimental investigation of the Flow Field around a Bridge Pier with Hooked collar" ICSE6 Paris - August 27-31A. Drysdale, DM (2008). 'The effectiveness of an aerofoil shaped pier in reducing down stream vortices and turbulence', University of Southern Queensland. ZM. Christensen. (2009). Reduction of Local Scour around Bridge Piers: Combined System of Aerofoil and Slot”, University of Southern Queenlan, Toowoomba. D. Gibson. (2010). Evaluating Comparative Perfommance of Various Shaped Bridge Pers: Experimental Investigation of Sediment Transport and Scouring" , University of Southern Queenlan. Melville, B.W. and Chiew, Y.M. (1999). Time scale for local scour at bridge piers. Journal of Hydraulic Engineering, ASCE, 125(1): 59-65. Ettema, R. (1980). Scour at bridge piers. PhD Thesis. University of Auckland, Auckland, New Zealand. Chiew, Y.M.( 1984). Local scour at bridge piers. PhD Thesis. University of Auckland, Auckland, New Zealand. Dey, S. (1995). Three-dimensional vortex flow field around a circular cylinder in a quasiequilibrium scour hole. Sadhana, Proc. Indian Acad. Sci., 20 : 771-785. Molinas, A. 2003. Bridge Scour in Non-uniform Sediment Mixtures and in Cohesive Materials: Synthesis Report. Report Nr. FHWA-RD-03-083. B. W.Melville and A.J. Raudkivi .(1997) "Flow Characteristics in Local scour at Bridge Piers", J. Hydr. Res. IAHR, 15, 373–380.