| Numerous spur dikes and groins had been built for the purpose of preventing stream bank erosion, or stabilizing channel alignments. In each purpose, groin angle and arrangement has been studied comprehensively through past studies. It is known that plane angle of groin has different influence on riverbed deformation. In this study, flume experiments with movable-bed were conducted in order to discuss characteristics of bed deformation around submerged groins for different plane angle for the purpose of finding the fundamental shapes of the submerged groin which are suitable for capture bedload and form a point bar. Tested groin models were set to various plane angles against the sidewall, from a right angle to an angle pointing upstream of nearly 80°. In results, the fundamental effect of groin angle is observed. As the angle becomes large, local scour around the tip of groin decreases. The scour volume increases because the scour holes formed on the downstream side increase in size due to flow passing over the groin model at an angle. Furthermore, it is shown that scour volume is considerably reduced by devising the shape of the groin. |
