The Effect of Geometric Parameters and Foundation Depth on Scour Pattern around Bridge Pier

Scour around bridge foundations is one of the major causes of serious damage to the bridge. In this study, the effect of shape, level and position angle of foundation on scour pattern was investigated experimentally. The experiments were conducted for 4 foundation shapes including; square, cylinder, aerodynamic along and across the channel, 5 foundation depths and 7 foundation alignments. The results show that the scour depth depends on the foundation depth, shape and foundation alignment to the approach flow. The best foundation shape which leads to minimum scour, was aerodynamic shape along the channel, square, aerodynamic across the channel and cylindrical shape, respectively. The results also show that positioning of foundation below the initial channel bed, leads to less values of scour depth around bridge pier. Also the best angle for positioning of foundation is zero, i.e. parallel to flow direction. Analyses of results also show that the appropriate level for positioning the foundation is 25 to 50 % pier diameter below the channel bed.