非恒定流作用下丁坝局部冲刷研究

Local Scour of Spur Dike in Unsteady Flow

丁坝水毁现象普遍存在且受多种因素影响,目前关于丁坝水毁的研究成果多是在恒定流条件下得到的,没能很好地解决丁坝水毁的实际问题。因此,通过水槽概化模型试验,在天然河流日均流量过程作用下,分别对比了相同重现期时年最大洪峰流量和有效洪水周期遭遇、年最大洪峰流量和半月最大洪水总量遭遇丁坝局部冲刷的程度,指出洪峰流量对冲刷深度起主导作用,洪水总量对坝头冲刷坑范围起主导作用,有效洪水周期对冲刷坑范围及冲刷深度均起主导作用;并对非恒定流作用下坝头冲刷坑的发展过程进行分析,认为随着冲刷坑下游沙垄形成与消亡的变化,冲刷坑范围并非随时间延长而增大。

Water damage phenomenon of spur dike is widespread and influenced by many factors,and the current research results on it is under the condition of constant flow,which can't be good enough to solve practical problems. Through flume model experiment,under the action of the average daily flow process of natural river,degree of local scour of spur dike was compared respectively with the same return period when maximum flow and flood period as a total annual maximum flood peak discharge and half maximum flood. The results showed that the peak flow plays a leading role in scour depth,the flood volume plays a leading role in scour scope,and effective flood period on the scope and scour depth of the pit are its leading role. Meanwhile,the analysis of the development of scour pit indicated that the range of the scour pit is not increases with time gradually.