ABSTRACT
The combination of permeable and impermeable spur dike was proposed to reduce severe local scour and to create diverse reverbed configuration. The purpose is to find out an optimum distance between pile-group and solid spur dike for reducing the local scour. We investigated the flow structure and bed deformation around a single spur dike downstream of a pile-group in an open channel. A series of experiments were conducted under emerged flow and clear-water scour conditions. In the cases with an upstream pile-group, the local scour was faded with a noticeable decrease in the depth and amount of bed erosion. The scour depth and volume were decreased as the distance increased from zero to four times the spur dike length. In the cases with a pile-group, flow near the spur dike became lower relative to the single solid spur-dike case. The flow structures around the combination of the pile-group and the spur dike were well simulated by a 2D numerical model and the reduction of the bed shear stress near the spur dike by the pile-group was demonstrated.
