考虑河床变形的涌潮数值模拟

Tidal bore is a unique natural landscape when tidal wave propagation to the estuary area, river-bed deformation causes discontinuous of tidal wave . the research of tidal bore is one of the hot and difficult problems of estuarine and coastal research field at present. In recent decades, the research bout tidal bore has been made considerable progress. The numerical simulation is one of the important technical means, but the previous studies was usually based on fixed bed conditions, namely, the riverbed deformation wasn't be considered. In fact, the sediment particle size in Qiantang estuary varies in the range of 0.02 ~ 0.04mm, and is apt to erosion and deposition, so that the river bed deformation become complex, and the physical model also indicates the difference of tidal bore height between the movable bed and the fixed bed.There is no literature reported about movable bed mathematical model of tidal bore. In this project, the field data is used to calculate the shear stress of the bottom boundary layer. The relationship formula between the shear stress and the carrying sediment capacity is established.Based on the reasonably determination of sediment parameters, movable bed mathematical model is proposed.The bore characteristics can be more fully understood.What's more,interactions of tidal bore and river bed deformation,mechanism of river bed deformation,can provide technical reference for river bed evolution,those contribute to propose scientifically government plans for macro-tidal estuary .

涌潮是潮波传播至河口地区，受地形影响变形后产生潮波间断的一种独特的自然景观，是目前河口海岸研究领域的热点和难点问题。近几十年来，涌潮研究已取得长足的进展，数值模拟已成为研究涌潮的重要技术手段，但以往多是基于定床条件下开展的，即不考虑河床变形的涌潮模拟.事实上，钱塘江河口泥沙中值粒径在0.02～0.04mm之间，易冲易淤，在涌潮作用下河床变形迅速、复杂，对动床条件下涌潮的模拟研究未见文献报告。本项目研究运用实测资料计算涌潮河段底边界层内近底切应力，建立涌潮作用下的挟沙能力关系式；通过水槽模型试验研究强涌潮条件下泥沙的起动规律；在此基础上，合理确定泥沙参数，建立动床条件下涌潮数值模型，考虑河床变形及其与涌潮的相互作用，提高涌潮预报的精度。通过该项目的研究能更全面地了解涌潮特点，分析强涌潮作用下河床变形的动力机制，丰富河口海岸学理论，从实践上指导强潮河口治江方案的制订和实施。

本研究通过水槽模型试验研究强涌潮条件下泥沙的起动流速和含沙量垂线分布规律；基于紊流猝发理论，建立涌潮作用下的平衡近底层含沙量表达式，并运用实测资料建立涌潮作用下的挟沙能力关系式；在此基础上，合理确定泥沙参数，建立动床条件下涌潮数值模型，考虑河床变形及其与涌潮的相互作用，提高了涌潮预报的精度。通过该项目的研究能更全面地了解涌潮特点，分析强涌潮作用下河床变形的动力机制，丰富了河口海岸学理论，从实践上指导强潮河口治江方案的制订和实施。