长江下游双涧沙守护工程局部冲刷水槽试验研究

Flume experiment of local scour around geotextile mattress for Shuangjiansha central bar protection in Lower Reaches of Yangtze River

双涧沙守护工程中的护滩潜堤与南北顺堤过渡段河床受越堤翻滚流作用冲刷剧烈,为此采用系砼块软体排进行护底。排体的守护范围是决定该段工程稳定的制约因素,而排体外缘冲刷坑最大深度是确定余排长度的关键因素。采用80、120和200三种比尺的水槽分别对潜堤过渡段不同部位进行冲刷试验,通过系列模型延伸法对比研究不同守护范围下的局部冲刷范围和深度。结果表明,护底宽度增加后,河床最大冲深值减小明显。

In the Shuangjiansha shoal protection project,severe bed scour would be caused by the tumbling overflow in the transitional zone between the submerged dike for beach protection and the north-south directional embankment.In prevention of this,flexible mattress tied with concrete blocks was applied to cope with the bottom protection.However,the protecting range of the mattress which was essential to the stability of the whole project needed to be determined by the maximum scour depth right adjacent to the mattress edge.In this study,comparative model experiments in three different scales were conducted,and the extent and the depth of the local scour under different protecting ranges were further investigated.The result shows that the maximum scour depth would be obviously decreased with the increase of the breadth of bottom protection.