三峡工程近期下游引航道口门区泥沙淤积分析研究

Study of sediment deposition in downstream approach channel of Three Gorges Project

对三峡工程运行初期下游引航道泥沙淤积机理及口门区泥沙淤积量计算方法进行了探讨。研究成果表明,在下游引航道口门附近,存在竖轴回流,产生回流淤积,在回流以内的港渠存在异重流,产生异重流淤积。口门区的回流泥沙淤积量与回流长度、水深、纵向平均流速、含沙量、历时等因素有关,可采用谢鉴衡公式计算下游引航道口门区泥沙年淤积量,并对公式中涉及的回流长度等关键参数给定了计算方法及数值,回流泥沙淤积量计算值与实测值进行了对比,两者较为一致。

The mechanism of sediment deposition in the downstream approach channel of the Three Gorges Project and the method to compute sediment deposition in the approach region are studied. The research results indicate there exists circumfluence in the approach region of the downstream approach channel which is the reason of sediment deposition. The density flow in the channel induces sediment deposition there. The sediment deposition amount in the approach region is related to the length of the circulating region, water depth, longitudinal velocity, sediment concentration and duration of inflow. It is appropriate to apply Xiejianheng＇s formula to compute sediment deposition in the approach region of the downstream approach channel, and the key parameters such as the eireumfluenee length and so on are presented. Comparison between the calculated and measured sediment deposition amount caused by the cireumfluence is made. The calculated sediment deposition amounts caused by the circumfluence are in good agreement with the measured values.