近期长江口北槽河道浮泥变化及影响因素研究

Research on recent changes of fluid mud and its impacted factors in the north passage of the Changjiang Estuary

基于多种较先进的观测仪器,对近期长江河口北槽整治工程实施过程中河道浮泥变化及相关的影响因素进行定点和走航观测。结果表明,近期长江河口北槽浮泥层在潮流速、悬沙浓度、盐度和地形等因素影响下,具有多种准周期性的振荡变化特征,其中小潮形成的浮泥厚度大于大潮形成的浮泥,同时北槽主航槽局部区段浮泥的形成和发展与陆海互相作用的动力结构环境的纵向和横向环流输沙有关。在大、小潮期间的不同环流输沙作用下,局部河段主槽内浮泥的存在,使北槽河道横断面分别出现不同的河槽形态,由于实测浮泥层容重均小于1.25 t/m3,可作为"适航"水深,通常通过即时疏浚清理航槽淤泥基本能保持设计通航水深。

Based on the data obtained by fixed and navigated observations with combination of multiple advanced appliances in recent years,the recent changes of the fluid mud and its impacted factors in the dredging north passage were analyzed. The results were shown as follows： the aggregated sediments could be main source for the formation of fluid mud occurred in the north passage. In addition,the change of the fluid mud in the north passage was of multi-vibrated characteristics with quasi-period resulted from the impacts of current velocity,the concentration of the suspended sediment and salinity. The thickness of the fluid mud formed in the spring tide was bigger than that in the neap tide. The formation and development of fluid mud in the local trunk of the north passage was directly associated with sediment transport of transverse circumfluence resultedfrom weak bended river channel type and weakly bended river configuration. Because of the sediment transport by different circumfluent actions during the spring tide and neap tide,the local shape of the transverse section in the main channel of the north passage varied with the change of the fluid mud. Due to the measured volume weight of below 1. 25 t / m3 in fluid mud,the water depth of the available navigation in the north passage was suitable if the prompt dredging in the channel could be carried out to maintain the designed water depth of the navigation.