河口海岸异重沙流成因机制与输移动态预测

Density current is widely settled in the estuarine and coastal zone. In recent years, with the depth of the harbor and the channel being deeper, density current has been researched focus on the coastal engineering field. In the near-shore region, the seabed soil suffered from various dynamic actions. Under the joint action of wave and current, the seabed property changes which results in the increase of pore water pressure, the seepage from the bottom of the sea bed soil, seabed soil liquefaction, fracturing of local soil, incipient and transport of the sediment, variation of the suspended sediment concentration, formation of the density current etc. With the different from the density current in reservoirs, this study is to explore the formation and operation mechanism and observation and prediction method of density current based on these physical conditions.. The effects of the wave and current on the formation and operation mechanism of density current will be considered, actual formation and transmission models of density current will be built up and the quantitative relationship between the formation of density current and the degree of seabed dynamical response will be studied in this project. Main research contents include: the physical and mechanical properties of density current under different response degree, such as the seepage from the bottom of the sea bed soil, seabed soil liquefaction, fracturing of local soil, incipient and transport of the sediment, variation of the suspended sediment concentration and formation of the density current; transportation mechanism of seabed surface density current under wave response, the principle of surface erosion, the scour and silting state point and process of density current, the formation, transportation and erosion mechanism of extreme density current under extreme sea environment on the conditions of seabed instability, the model of the process of sudden siltation and erosion. . This project is the inter-discipline of marine soil mechanics and engineering sediment industry and will play important role in promoting the development of estuarine and coastal science. At the same time, the research production can provide theoretical reference to the site selection, construction, preventing and treating silt of the port fairway in offshore engineering, pollutant release, transportation in environmental engineering and the marine structure failure in geotechnical engineering etc.

本项目考虑波流作用底床条件对异重沙流形成及运移机制的影响，建立河口海岸条件的异重沙流形成与运移模型，研究异重沙流形成与底床动力响应程度间的定量关系。包括：研究海床在不同波浪响应程度下的物理力学特性及运动特性，如海底床土体内渗流以及底床土体液化、局部土体劈裂、泥沙起动、集体运移、浓度变化、异重流形成等过程；研究不同波流响应条件下海床表面异重流运移机制、床面侵蚀规律以及异重流冲淤点状态和过程；研究极端海况条件下的底床失稳、极端异重流的形成与运移侵蚀规律，建立河口海岸骤冲骤淤计算模型。.项目是海洋土力学和工程泥沙行业的交叉学科，对促进河口海岸学科的发展具有重要科学意义。

河口海岸黏性泥沙的流变特性、运动特性及其与波浪之间的相互作用，对于预测和解决河口异重流的形成、运动以及衰减过程起重要作用。河口异重流的发展过程决定着河口是否可以正常维持径流排入外海，因而研究河口黏性泥沙物理特性，以及河口异重流形成-运动-衰减过程具有重要的研究价值和广泛地应用价值。本研究以黏性泥沙作为研究对象，通过实验和理论研究，系统探索黏性泥沙的流变特性和运动规律；波浪作用下水流-泥沙分层流体流场分布特征；异重流形成后与上游浑水分界线；以及水流-泥沙分层流的流动稳定性问题等。此外，项目就波浪与浮泥之间的相互作用建立两层数学模型，对幂律流底泥输移、幂律流动力场分布、幂律流流动稳定性进行了理论研究。项目研究过程中，作为河口的一个缩尺对比，对水库异重流也进行了探讨。研究发表论文13篇；培养学生5名：博士2名 ，硕士3名；举办国际/国内会议两次；获得省部级一等奖一项，特等奖一项；授权计算机软件著作权两项。