| The study of estuarine tidal current sediment carrying capacity is of great significance for understanding the process of water and sediment movement,analyzing the law of estuarine evolution,guiding channel dredging and planning the placement of dredged soil.Because the estuarine tidal flow is a typical non-uniform,unsteady and periodic water movement,the energy method,minimum energy consumption method and empirical analysis method which are commonly used in previous studies may have some limitations in their application.In the study of tidal current sediment carrying capacity,the effective shear force method of flow on sediment transport is used,that is,the effective part of flow on sediment particles is extracted from the total shear force,which can eliminate the effects of non-uniform,unsteady and physical resistance of water body.Therefore,in this study,the effective shear method is applied to the calculation of tidal current sediment carrying capacity,and the reliability of the formula is verified by the combination of statistical analysis and laboratory experiments.at the same time,the effective shear method is used to improve the sediment module in Delft3 D model,and the numerical calculation of tidal current sediment carrying capacity is carried out,in order to provide further data support for channel siltation and regulation.Through research and analysis,the main conclusions are as follows:1.The tidal current sediment carrying capacity formula based on effective shear force has high calculation accuracy and strong practicability.Based on the measured data of 10 typical estuaries in China,the effective shear method,energy method,extreme value method and empirical method are compared and tested.it is found that the calculation result of tidal current sediment carrying capacity formula based on effective shear force has high accuracy.and it has strong applicability in the estuarine area.In addition,there is no need to determine the rate of measured data when using this formula,so it is convenient to be used in areas where there is no data or lack of measured data.2.The calculation method of tidal current sediment carrying capacity based on effective shear force reflects the dynamic process of sediment flocculation in the estuary and has good numerical reliability.Based on the tidal current sediment carrying capacity formula of effective shear force and the dynamic principle of estuarine sediment flocculation,the particle size,bulk density and the proportion of sediment flocculation are deduced.Through the calculation of this formula,the average particle size of flocs in the Yangtze River Estuary is 43.972 ? m.Compared with the results of indoor still water flocculation experiments,it is found that the difference between them is less than 5%.It shows that the expression of flocculation parameters in the formula of tidal current sediment carrying capacity based on effective shear force has good reliability.3.The improved sediment module based on effective shear force embedded in Delft3 D model has a good application effect.After embedding the effective shear sediment transport formula considering the effect of flocculation into the Delft3 D model,it is found that the calculated results of the improved sediment module are closer to the measured sediment data than the default sediment module,indicating that the effective shear sediment transport formula considering the effect of flocculation is more compatible in the Delft3 D model.Moreover,the improved sediment module needs to set and debug fewer parameters,the operation is more convenient,and the engineering practicability is strong. |
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