长江上游大比降卵砾石河段水流强度指标研究

Study on the hydraulic intensity index of the high gradient gravel river in upper Yangtze River

文章基于长江上游河段内寸滩站水文泥沙实测资料,围绕决定水流强度大小的影响因素,针对长江上游大比降卵砾石河段的水面比降、相对光滑度、粒径组成等特点,通过比较分析以往经典输沙强度公式,在此基础上将各物理量无因次化,借助多元回归分析对研究河段内的水流强度指标形式进行拟合,主要探讨了决定水流强度的影响因子及影响程度大小。结果表明:通过比较各类水流强度指标与输沙强度的相关性,切应力类指标较好,而平均流速类和水流功率类指标的表征能力欠佳,在切应力指标中,Einstein式的相关性最好;假设水流强度与各影响因子成幂次关系,得到了描述水流强度的表达式:Θ=k(h/d)a1(V(γs/(γ-1)gd(1/2))a2Ja3;通过实测资料,借助多元回归分析法对公式系数进行拟合,得到了能准确预测长江上游大比降卵砾石河段水流强度的表达式:Θ=4.755(h/d)0.0477(V/γs/(γ-1)gd(1/2))1.1752J0.9275.

Based on the surface slope,relative smoothness,granulometric composition of the upper Yangtze River,by using Cuntan station,the paper made the measured data analysis of the existing main hydraulic strength index,and the intensity of sediment correlation.Main influencing factors and according to the strength of hydraulic,hydraulic strength and all the factors into the exponential relation,each physical quantity after the dimensionless gets big slope gravel river hydraulic strength expression.The results show：from the comparison of all kinds of hydraulic strength index and the correlation of intensity of sediment,the shear stress class index is better,average flow velocity and stream power index sign has poor ability,and in index of shear stress,the correlation of Einstein （1950） is best;if the hydraulic strength has the exponential relationship with various impact factors,the expression to describe the strength of hydraulic is：Θ=k（h/d）a1（V/√（γs/γ-1）gd a2,Ja3;through the measured data,by means of multivariate regression analysis method to fitting formula coefficient,expression is got to accurately predict the upper Yangtze river gravel river hydraulic strength of large gradient：Θ =4.755（h/d）00477（V/√（γs/γ-1）gd）1.1752J0.9257.