Experiment Study on Local Scour of Submerged Spur-Dike Group
|關鍵字:||丁壩群;局部沖刷;浸沒式丁壩;spur-dike group;local scour;submerged spur-dike|
Spur dike, including permeable or impermeable, and submerged or emerged, is a general method of river engineering in our country. However, different arrangements and flow conditions of spur dike will cause complex change of scouring behavior. Most of early studies focused on the local scour and contraction scour of the single spur dike, rarely compare the scouring mechanism of spur-dike group during different ratio of the flow depth to the dike height. Spur dikes usually need to form as group to bring obvious effect on river engineering. Therefore, this study was to investigate the effect to local scour on submerged spur-dike group of different ratio of the flow depth to the dike height. In order to investigate the mechanism of sediment transport around the spur dike field and the local scour of spur-dike group, this study uses long straight flume under non-uniform grain size condition, and designs cases with different ratio of the flow depth to the dike height. Experimental results show that, when the degree of submergence ratio increases, the local scour at the spur-dike head will lead to the adverse bed slope of spur-dike field incline, which is not conducive to sediment deposition. Lowering the height of the first spur-dike in the spur-dike group can weaken the vertical vortex in front of the spur-dike head, and reduce the local scour depth and the sediment loss in the dowmstream spur-dike field.