感潮河段支流口门堤头结构形式研究

Structural form of levee head at entrance of tidal river's branch

感潮河段支流口门引排水枢纽受用地条件限制常距江较近,口门区水流受主河道涨落潮牵制作用明显,水流流态复杂,极易造成口门区泥沙淤积、岸坡冲刷及引航道横流超标等工程问题。为此,设计出可以改善感潮河段支流口门流态的梯级堤头结构形式。物理模型试验结果表明:在涨潮引水情形下,主河道水流折冲转向入引河的夹角减小,水流更为平顺地进入河道,减小了水流对河岸的冲刷,同时减小了引航道口门横流流速;在落潮排水情形下,堤头上下两级平台间可供水流通过,减弱水流顶冲主河道的强度,使得堤头下游回流范围减小,有利于河势稳定。

The junction located at the branch entrance of tidal river is always close to the main river due to limited land conditions,so the branch mouth flow is significantly affected by the tidal flow of the main river,and the flow pattern is complex.Thus engineering problems such as siltation,bank erosion,cross flow exceeding standard in approach channel,etc.appear easily at the entrance area.Therefore,a step structural form of levee head was designed to improve the flow condition.The results of the physical model tests show that the angle between the main river flow and pilot river flow decreases,and the erosion of river bank and the cross flow in the approach channel on the flood tide diversion case decrease as well.Meanwhile,the increase of the area of water flow and the decrease of river erosion lead to the reduction of recirculation range,which is conductive to the stability of river in the drainage tide ebb.