Abstract: The rational formula method which belongs to hydrologic analysis and calculation methods of small bridges and culverts is widely applied in the industries of highway,railway and water conservancy at home and abroad because of its simple reasoning formula and clear physical conception of parameters.This paper summarizes the fundamental form of the rational formula systematically.Based on the application of different rational formulas and the comparison between the formulas and other methods,it proposes the existing problems of the rational formula in application,such as the uncertainty of calculation result,unnecessary connection between the calculation result precision and the formula structure,unobvious advantage of the rational formula compared with the empirical formula,and etc.In the end,the paper puts forward three suggestions,the first is to enhance the parameter research of runoff yield and concentration in watershed,the second is to develop the research on the rational formula structure,the third is to strengthen the research on the rational formula applicability in overseas.

Key words: small bridges and culverts, hydrologic analysis and calculation, rational formula, formula structure, parametric analysis

摘要： 小桥涵水文分析计算方法中的推理公式法,产流机理清晰、参数物理概念明确,在国内外公路、铁路、水利等行业得到广泛应用。文中较系统总结了小桥涵水文分析计算推理公式的基本形式,通过不同推理公式的应用及其与其他方法的比较实例,总结提出了推理公式在小桥涵水文分析计算应用中存在的问题:计算结果存在较大的不确定性;计算结果的精度与公式的结构没有必然联系;推理公式与经验公式相比优势不明显等。在此基础上给出了关于小桥涵水文分析计算方法中有关推理公式应用的3点建议:一是加强特小流域产汇流参数的研究;二是进一步开展推理公式结构的研究;三是加强推理公式在国外适应性研究。

关键词: 小桥涵, 水文分析计算, 推理公式, 公式结构, 参数分析