The Variation of Scour Depth near Vertical and Inclined Cylindrical Bridge Piers: An Experimental Study

Abstract

The stability of bridge piers against scouring phenomena require to estimate the scour depth carefully at different hydraulic condition to ensure safe design. In this study, laboratory experiments were carried out to examine and compare the scour depth for vertical and inclined cylindrical piers with downstream direction under clear water scour conditions. The measured scour depth in front of three inclined configurations (ϴ = 10°, 16° and 22°) for single cylindrical pier was compared to that observed at vertical cylindrical pier (ϴ = 0°). The experiments were conducted at four flow intensities (V/VC=0.495, 0.714, 0.824 and 0.989) for sand bed material of d50=0.72 mm. The obtained results revealed and confirmed the inverse relationship between the measured scour depth and the angle of inclination of pier, whereas the maximum and the minimum scour depth was observed at ϴ = 0°, and ϴ = 22° respectively. The results of this study showed that the scour depth near threshold conditions (V/VC=0.989) can be reduced approximately by (5%, 10%, and 15%) for inclined piers with (ϴ = 10°, 16° and 22°) respectively. Furthermore, by assessment of five existing formulas, new modified empirical formula has been proposed for scour depth estimation of inclined piers with ± 9% error margins.