基于最小能耗原理的明渠水力最佳断面研究

最佳水力断面推求是一个十分有意义的理论问题。基于最小能耗原理,采用三个最具代表性的表达式,分别推求了梯形断面渠道的最优宽深比,并就边壁与河底糙率不同时的最优断面进行了探讨。结果表明:利用最小能耗原理,可以推求梯形断面的最优宽深比,而且根据三种表达式所得结果是相同的;对于梯形断面渠道,当河岸糙率与河底糙率比值增加时,最优宽深比将有所增大;当边坡系数增加时,最优宽深比也将有所增大;在河岸缺少约束的条件下,河流具有向宽浅发展的内在属性。

Study on Optimum Section Based on the Principle of Minimum Energy Consumption

The ascertain of optimum hydraulic section is a very important theoretical problem. Based on the principle of minimum energy consumption, the optimum ratio of width to depth of trapezoidal channel is deduced by using three representative formulas. And the optimum section is discussed when the roughness of the wall and the river bed are not equal. The results show that the optimum ratio of width to depth of the trapezoidal cross section can be derived by using the principle of minimum energy consumption, and the results obtained by the three expressions are consistent. For trapezoidal channel, the optimum ratio of width to depth will increase when the ratio of roughness between river bank and river bottom increases, and the optimum ratio will also increase when the slope coefficient increases. In the absence of constraints on the banks, the river has the inherent attribute to become wider and shallower as it develops.