Özet:

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.

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