The Effect of Different Spur Dike Shapes on Bridge Abutment Scour in Compound Channel

Scouring is one of the most important factors threatening the stability of bridge abutments on rivers. Most of bridge abutments are located in floodplains. In the present study, the effects of four different single spur dike shapes including the simple spur dike, T-shaped spur dike, L-shaped spur dike with a clapper toward downstream, and L-shaped dike with a clapper toward upstream on the maximum scour depth at the abutment of a bridge, are studied. The present study was conducted on a rectangular flume with a width of 1m, a length of 12m, and a height of 60cm. The compound channel was constructed in a symmetrical and rectangular shape with the width of the main channel 20 cm and the width of the floodplains 40 cm. Spur dikes with three lengths including the 4, 8, and 12-cm lengths were installed as single spur dikes at 4, 8, 12, 16, 20, 24, 28 and 32-cm distances from the abutment. The results indicated that the simple spur dike, the T-shaped spur dike, the L-shaped spur dike with a clapper toward downstream and the L-shaped spur dike with a clapper toward upstream reduced the maximum scour depth at the abutment by 80%, 93%, 96% and 78% respectively.