Investigation of Local Scour Around Group Bridge Pier with Different Shapes

In this study, the establish on laboratory experiments for computing the depth of local scour (ds) around group bridge pier. For this purpose, fifteen models of bridge piers were constructed and tested, divided into five groups, of each group containing three bridge piers with the same specifications. The diameter of upstream bridge piers (D1) was varied to 2, 4, 6, 8, and 10 cm, and diameter of downstream bridge piers (D2) 10 cm for all. The spacing (S) between the bridge piers was varied three times 20, 30, and 50 cm for all groups. Considering the effectiveness study of upstream flow conditions, the size of diameters of bridge piers, the spacing between bridge piers and medium size of bed material on the maximum scour depth and scour pattern around bridge piers. The study was conductedby employing a physical hydraulic model for bridge piers operated below subcritical flow, clear-water condition and exploitation uniform cohesionless sand as bed material. The experimental results showed the scour depth (ds) increasing whenever increasing the upstream diameter (D1) of bridge pier and decreasing whenever decreasing the spacing (S) between bridge piers. The dimensional analysis techniques and statistical program were used for locating a new empirical formula with the facilitate of the experimental information; this formula is for calculating the maximum scour depth at bridge piers.