长江下游福姜沙河段边心滩演变及对航槽冲淤影响研究

Study on the Deformation of the Point/Channel Bar of the Variable Section of the Tidal Current Limit of Yangtze River and Its Influence on the Scouring and Silting of Dredged Channel

潮流河段水沙输移条件复杂,边心滩活动性强,其演变过程及机理的揭示,有助于掌握和预测边心滩演变对航道条件的影响趋势.以长江潮流界附近的福姜沙河段为研究对象,通过对1999~2017年实测水文、泥沙、地形资料的分析,研究表明:①1999~2017年期间,靖江边滩经历了3个较为完整的周期性演变,对应时段为1999~2002年、2002~2010年和2010~2016年,2016年汛后开始新一轮演变;②靖江边滩的切割发生在大水年,当上游径流流量(大通站)高于50000m^3/s尾部时大幅冲刷,高于60000m^3/s尾部出现切割,且持续天数越长,切割沙体的体积越大;③洪季靖江边滩和双涧沙沙舌每冲刷100×10~4m^3泥沙,约44×10~4m^3淤积在福北水道设计航槽内,在洪季靖江边滩和双涧沙沙舌冲刷、径流量增加对福北水道设计航槽淤积的影响权重分别为59.3%和40.7%本研究成果,可为福北水道航道整治及疏浚维护提供理论参考.

The hydrodynamic forces and the sediment transport conditions of the variable section of the tidal current limit in the lower reaches are complex and the activity of the point and channel bars is strong,so to reveal the deformation process and mechanism can help us master and predict the influence degree of the deformation of the point and channel bars on the channel conditions.In this paper,the variable section of the tidal current limit in the lower reaches of the Yangtze River-Fujiangsha waterway was taken as the study object and the measured hydrological,sediment and topographic data from 1999 to 2017 were taken into consideration.①from 1999 to 2015,Jingjiang point bar has experienced three complete cycle evolution,and the cycle period is divided into 1999~2002,2002~2010 and 2010~2016,and the new round of cycle evolution begins after the flood season in 2016;②the cutting of Jingjiang point bar occurs in the flood year,and when the upstream runoff discharge(Datong station)is higher than 50000 m^3/s,the significant scouring occurs,and the cutting occurs when it is higher than 60000 m^3/s,and the longer the lasting time is,the greater the volume of cutting sand body is;③as for 100×10~4 m^3 of sediment scouring in the head bottomland of Jingjiang point bar and Shuangjiansha,there is about 44×10~4 m^3 silted in the Fubei waterway design dredged channel,and the influence weight of the head bottomland scouring and the increase in the runoff volume in the Jingjiang point bar and Shuangjiansha in the flood season on the siltation of Fubei waterway design dredged channel is 59.3%and 40.7%respectively.