【作者】 英晓明；

【导师】 丁平兴；

【作者基本信息】 华东师范大学 ， 河口海岸学， 2011， 博士

【摘要】 洋山深水港位于崎岖列岛内,毗邻杭州湾,是上海港新建的大型深水港。洋山海域具有多汊道输水输沙的特征,潮流强,含沙量高。自2002年以后,港区先后实施了小洋山-镬盖塘汊道、大乌龟-颗珠山汊道和将军帽-大指头岛汊道封堵以及陆域填充和港池疏浚工程。在汊道封堵之后,港区曾出现大范围的淤积现象,一度影响后续工程规划的实施。工程施工引起的海床冲淤演变规律和原因是迫切需要解决的关键问题,对其进行深入研究在科学及应用上均有重要意义。本文利用1998-2010年的实测地形资料,定量分析海床冲淤演变的时空变化规律。研究结果清晰地揭示海域地形随工程进展的冲淤变化特征。堵汊工程结束后的第一年内在汊道两侧出现明显的淤积带,但是淤积率在下一个年度显著下降；港区内部东南区域每年都出现淤积；淤积从2007-2009年增加,但以后呈下降趋势。为维护航运所需15m水深,港池前沿开挖是必要的,而且经过开挖也能够维护航运所需水深。实测资料表明,大潮时落憩时刻含沙量最高。在洋山海域水体和悬沙输运存在明显差异,直接描述悬沙净输运更准确合理。欧拉余流在水体长期输运中占主导地位,平流输运和潮泵作用是洋山海域悬沙输运的主要动力因子,由于潮动力混合较强,垂向输运作用很小。2006年港区中南部悬沙净输运指向大山塘北侧,可能是该地区淤积的原因之利用工程间歇期和港区海域环境经历一段较长的适应调整期,观测和估算各汊道的水沙通量对于评估港区海域的淤积态势及洋山港的持续发展规划有重要的参考价值。本文利用ADCP和OBS在洋山港走航和定点观测的数据,采用通量守恒原理,使用横向均匀、垂向时变的网格,经过时间和空间插值,计算得到大小潮期间洋山港5个主要汊道断面的水沙通量。分析表明,港区内净输进沙约5.44万m3/天(2008年8月)。以此作为洪季的日平均净输沙量,则洪季(三个月)港区内净输进沙约489.4万m3,港区内局部表现为淤积。颗珠山汊道洪季(三个月)净输出沙量约231.3万m3,是港区内重要的出沙通道。为分析海床冲淤演变机理,利用Delft3D建立了洋山海域嵌套模型。在对模型进行充分率定和验证基础上,又对三个堵汊工程引起的地形演变进行了后报验证,模型基本上能够刻画堵汊工程引起的地形冲淤演变特征。水位壅高导致的流速减小是引起淤积的主要动力机制。本文又对港区未来可能进行的堵汉工程进行了地形演变预测,若实施南面两个汊道封堵,不仅在汊道附近产生明显的淤积带,而且可能在港区内西部产生大范围的淤积区。更多还原

【Abstract】 Yangshan Deepwater Harbor, located in the Qiqu Archipelago adjecnt to Hangzhou Bay, is the new deepwater harbor of the Port of Shanghai. The study area features a series of islands with complex hydrodynamics and high sediment concentrations。Its construction since 2002 entails three types of engineering projects:closing a series of inlets, i.e., inlet between Xiaoyangshan and Huogaitang Island, inlet between Dawugui and Kezhushan Island and inlet between Jiangjunmao and Dazhitou Island; land reclamation and dredging. After the construction of 1,2 and 3, these engineering projects caused a series of morphological changes in the area. Because of the serious sedimentation in the harbor area further construction of the planned harbors has been stopped for the time being. Research on the sedimentation and its causes is urgently needed for the decision concerning further construction of more harbors.In this paper we analyze the morphological changes in the harbor area using bathymetric data collected from 1998 to 2010. Especially since 2004 bathymetry in the area has been surveyed every year, making it possible to analyze the spatial and temporal variation of sedimentation-erosion in detail. The analyses provide a good insight into how the morphological changes are related to the various projects of the harbor construction, and how the changes develop in time. It is shown that in the year immediately after an inlet was closed accretion occurred on both sides of the closure. The sedimentation rates decrease significantly in the following years. The SE zone of the inner harbor area continuously accreted. Accretion accelerated from 2007 to 2009 but decreased thereafter. The results of the analyses indicate that routine dredging will be necessary to maintain the requisite 15-m depth requirement for berths, but a regular dredging routine is feasible.It is shown that suspended sediment concentration (SSC) is maximum at ebb slack during spring based on observed data. The obvious difference exists between water and suspended sediment residual transport, and it is more accurate and reasonable that calculating residual sediment transport directly. Euler transport is predominant role of water long-period transport, horizontal advection and tidal pumping take primary role in suspended sediment transport in the study area, the contribution of vertical transport is small due to strong mixed tide.The net suspended sediment transport for several stations in middle and south inner harbor area are oriented to north of Dashantang Island in 2006, which may be one of the reasons of deposition.It is significant for evaluating trend of harbor morphological change and planned harbor layout by measuring and calculating water and sediment fluxes of key transects, after the pause time of engineering and a longer time of adaption and adjustment of the harbor area itself. In this paper, the instruments of ADCP (Acoustic Doppler Current Profile) and OBS (Optical Backward Scatter) were applied to the five key cross-sections (CS) in the Yangshan Harbor to observe profiles of water depths, flow velocities and SSCs, respectively. Based on the flux conservation principle, the fluxes of water and sediment were calculated by the temporal and spatial interpolation on a horizontal-uniform-and-vertical-varying mesh. The net flux for sediment moving into the harbor area is about 54 400m3/day in August,2008. This value can be taken as the daily-averaged net sediment transportation rate for flood seasons, and based upon which, the net inflow sediment for a flood season (three months) is about 489 400m3, and the harbor area is in the state of deposition locally. The Kezhushan inlet is the main outflow passage for sediments, through which about 231 300m3 of sediments move out of the harbor in a flood season.For a better understanding of the mechanisms responsible for the observed morphological changes a detailed Yangshan waters hydrodynamic and suspended sediment model is developed based on Delft3D. The detailed model can simulate the morphological change induced by inlet closures basically after verified bed level changes induced by the three inlet closures based on parameters calibration and verification. The model results provide insights into how the morphological changes are related to the changes in hydrodynamics induced by the closures of the inlets. The paper predicts morphological change induced by planned inlet closure. Not only deposition belts occur near the inlet closure, but also large areas of deposition occur in western part of the inner harbor if the south two inlets are closed.更多还原