水库变动回水区泥沙分选数值模拟研究

Numerical Simulation Study on Sediment Sorting in the Fluctuating Backwater Area of Reservoir

为研究水库变动回水区推移质泥沙分选特性,考虑泥沙非均匀性的影响,利用Riemann解求解双曲型方程的Godunov格式的有限体积法求解浅水方程和Hirano活动层模型,建立了水库变动回水区泥沙分选数学模型,并利用物理模型所测变动回水区的水位和淤积高度对泥沙分选数学模型进行验证。最后根据水库的实际运行情况,对变动回水区在枯水期小流量低水位、水库充水及库水位消落情况下的推移质泥沙沿程分选进行数值模拟,模拟结果可较好地反映变动回水区床沙级配变化的规律,表明该模型可应用于实际水库运行时变动回水区的河床演变数值模拟,为航运、防洪提供一定的依据。

In order to study the characteristics of sediment sorting in the backwater area,considering the influence of non-uniform sediment,a two-dimensional model based on two-dimensional shallow water equations and the active-layer approach of Hirano was employed and some experimental data including water level and elevation of river bed produced by a scaled physical model was used to verify this numerical model.Finally,according to actual reservoir operation,the numerical model was applied to simulate sediment sorting during withered water period,filling reservoir and drawdown of reservoir and reflect the variation characteristics of sediment gradation in fluctuating backwater area.The results show that the simulation results can reflect the characteristics of sediment gradation in fluctuating backwater area pretty well and the numerical model can adapt to the numerical simulation on riverbed evolution in fluctuating backwater area,which can provide a certain scientific basis for shipping and flood control.