河岸陡峭度对冲积河流平衡河道形态的影响

Influences of bank steepness on the channel shape of alluvial river

河岸抗冲性对河流横断面形态影响显著。以水力半径分割方法为基础,采用等腰梯形过水断面,以河岸陡峭度代表河岸的抗冲性,利用变分方法研究冲积河流达到平衡状态时,河岸抗冲性对河道横断面形态以及输沙能力的影响。研究结果表明:河岸陡峭程度减缓时,平衡河道形态变得宽浅,相反变得窄深;河岸陡峭度变化对水力几何形态关系式中的相关变量指数几乎没有影响,仅仅影响水力几何形态关系式中的系数。随着河岸陡峭度增加,河流达到平衡状态时横断面形态变得窄深,河道最大输沙率增大。

There is a significant impact on the cross-section shape of the river by anti-scour ability of the riverbank.Based on the hydraulic radius segmentation method,taking isosceles trapezoid as the cross section,and the bank steepness as the anti-scour ability of bank,the variational method is used to analyze the influence by the anti-scour of bank on the cross-section shape and sediment transport capacity of the channel when the alluvial river to an equilibrium state.Results show that when the bank steepness slows down,the equilibrium channel shape becomes wide and shallow,on the contrary,it becomes narrow and deep.The change of bank steepness has little effect on the relevant variable index in the hydraulic geometric relationship,but only affects the coefficient in the hydraulic geometric relationship.During the increase of bank steepness,the cross-section shape becomes narrow and deep when the river reach equilibrium,and the maximum sediment transport rate of the river increases.