射流作用下不同沙床动态冲坑变化规律的试验研究

Experiment on change law of dynamic scour in different sand bed under the role of jet

基于泥沙动力学和射流冲刷理论,对粗沙沙床和中沙沙床在某一流速下进行不同靶距的淹没射流实验,通过高速摄像机捕捉动态冲坑在短时间内的发展变化,分析了在前10s和前1s内的坑深发展规律。并将前1s等分成24个时间段分析其细微变化。结果表明:冲坑深度在前10s内基本呈对数规律发展;射流冲刷刚开始时中沙沙床冲坑深度的发展趋势有时滞后于粗沙沙床;冲坑深度随时间有先增加后减小的趋势,在此流速下存在一个最优靶距。此实验的研究成果在疏浚工程施工作业时具有一定的参考价值。

Based on sediment dynamics and jet erosion theory ,the paper carried out submerged jet exper-iment of different target under certain velocity of the erosion of sand bed and fine sand bed .Through cap-turing the change of scour hole in short time by using high-speed camera ,it analyzed the law of this hole depth before 10s and 1s.The first 1 second is separated into 24 time periods to analyze the subtle change .The results show that scour depth is logarithmically before 10 s; the trend of the fine rustle bed lags the erosion of sand bed at the beginning of jet scour ;the scour depth demonstrates the trend of first increase and then decrease and exists an optimal target under this velocity .The result has certain refer-ence value for the construction of dredging .