新孟河感潮河段支流口门闸下极限冲刷试验研究

感潮河段支流口门外江侧水流受涨落潮牵制作用明显,水流流态复杂,为保证河道堤防安全,避免在大流量引、排水时河道严重冲刷,危害临近建筑物,对闸下冲刷展开研究十分必要。以新孟河延伸拓浚工程界牌水利枢杻为例,构建1:50物理模型开展试验,结果表明:若新开河被开挖至粉砂层,由于粉砂起动流速较小,极易被水流冲起造成河道严重冲刷;由于水流在软硬介质边缘处会产生漩涡,不停的淘刷坑底,使冲刷坑不断加深,所以在进行建筑物护底设计时,应全河段宽度范围内进行防护;根据感潮河段水流受涨落潮牵制作用的水动力特征,可以有针对性的对主流路上冲刷较为严重的区域建筑物进行防护。

Experimental study on ultimate scour at downstream of sluice gate at an estuary outlet of Xinmeng River

The branch exit flow at tidal river is significantly affected by high and low tide，and the flow pattern is complex. It is necessary to study the scouring condition under the sluice gate that is located at the estuary outlet of a branch tidal river, so as to prevent severe river erosion and avoid the damage to the adjacent buildings when conducting diversion or drainage of large flow. In this paper, taking Jiebei water conservancy engineering on Xinmeng River as a case, a 1:50 physical model was built to carry out a series of tests. The test results show that it is easy to cause serious scouring to the channel bed of Xinkai River, a tributary of Xinmeng River, if it is dug into the silty sand layer that has low incipient velocity; as the current generates vortexes at the edge of soft and hard media and it continually scour the bottom of the pit, a series of measures should be taken to protect the river bed in whole width of the river; the building protection design can mainly aim at the severe scouring area on the mainstream pass according to the hydrodynamic characteristics of the tidal flow.