Author(s): Sayed H. Sadat; Akihiro Tominaga
Linked Author(s): Akihiro Tominaga
Keywords: Spur dike; Pile-group; Local scour; Flow structure; Mitigation
Abstract: In this paper, we investigated flow structure and bed deformation around a single spur dike downstream of a pile-group in an open channel. The purpose was to find out an optimum distance between pile-group and spur dike for reducing the local scour. For comparison, a single impermeable spur dike (conventional type) without the pile-group was also evaluated. A series of experiments under emerged flow and clear-water scour conditions were conducted. 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 effect of pile group was limited to the distance between pile-group and spur dike. The scour depth and volume were decreased as the distance increased from zero to four times the spur dike length. The maximum scour depth at a distance four times the spur dike length was reduced to a minimum which is about 39 percent smaller than that of a zero distance. Flow velocity near the nose of spur dike was higher in the conventional type spur dike. In the cases with a pile-group, flow near the nose of spur dike became lower relative to the conventional case. But, in the main stream the flow increased as the pile-group and spur dike distance increased.
Year: 2014