Experimental study of local scour around a vertical pier in cohesive soils

Estimation of maximum scour depth is an important factor in designing structures that are embedded in rivers. Using a hydraulic model, the mechanism of local scour around bridge piers embedded in cohesive soils has been studied. Experiments were performed in a ume; 22 m long, 0.77 m wide and 0.60 m deep, with a pier of 0.1 m in diameter. Also, three types of cohesive soil with dierent percent clay were used. While changing parameters, such as current velocity, ow depth, initial moisture content, clay percentage, and undrained shear strength, in each experiment, the scour depths were measured. The measured data were adjusted by hyperbolic law. Using dimensional analysis, a relationship between the ultimate scour depth and eective parameters was developed. Finally, the ultimate scour depths obtained by the experiments were compared with those calculated by empirical equations