深中通道沉管隧道试挖槽回淤特征研究

Back silting analysis of the trial dredged-trough for immersed tube tunnel of Shenzhen-Zhongshan Link

文章基于深中通道工程试挖槽为期一年的水下地形及水文观测资料,研究了试挖槽回淤特征及试挖槽水域的水沙环境,探讨了试挖槽回淤的原因。研究结果表明:(1)试挖槽回淤呈现洪季明显较大、枯季明显较小的变化特点;(2)试挖槽边坡和槽底淤积平面分布整体呈北部和东部大、南部和西部小的特点;(3)试挖槽回淤强度呈大潮-中潮-小潮逐渐减小的变化特点,与试挖槽水域底部含沙量随大潮-中潮-小潮逐渐降低的变化趋势基本一致;(4)试挖槽槽内淤积物与悬沙物质及周边滩槽细颗粒泥沙基本相同,试挖槽淤积的泥沙主要为随潮流搬运输移的泥沙,上游方向泥沙的影响大于下游方向。试挖槽槽内淤积形式以悬沙落淤为主。

Based on mass underwater topography data and hydrology data observed during nearly one-year period for the trial dredged-trough for immersed tube tunnel of Shenzhen-Zhongshan Link,the back silting characteristics of the trial dredged-trough and the hydrodynamic and sedimentary environment of the project site were analyzed in this paper.Sediment supply and the cause mechanism of the back siltation of the trial dredged-trough was studied finally.The main research conclusions were showed as follows:(1)The back silting rate of the trial dredged-trough was obviously larger in the flood season than that in the dry season;(2)The silting thickness in the north and east slope was larger than that in the south and west slope of the trial dredged trough,and the silting thickness in the northern half was larger than that the southern half of the trough bottom;(3)The back silting rate of the trial dredged-trough changed from large to small during flood tide to neap tide,and the suspended sediment concentration at the protect site changed from large to small during flood tide to neap tide;(4)The sediment type in the test trench was basically same as the suspended sediment and the fine sediment in the surrounding seabed,so the sediment deposited in the trial dredged-trough mainly came from the suspended sediment transporting by the tidal current.