反弯点简化三角形单位线桥梁流量计算方法研究
Research on triangle unit hydrograph method for bridges flow calculation based on points of inflection simplification

以水文资料普遍缺乏的中小流域桥梁流量计算为研究对象,提出一种基于瞬时单位线反弯点简化的三角形单位线流量计算方法:对比分析瞬时单位线和简化三角形单位线线形,提出基于反弯点简化的三角形单位线法;建立三角形单位线模型,推导模型参数涨水历时、退水历时和峰值的数学表达式;借鉴影响线加载理论,将设计(检定)频率雨量系列、实时雨量系列当作移动荷载组在三角形单位线上加载,推求设计(检定)暴雨和实时暴雨产生的地表径流,为新建桥梁设计流量计算、既有桥梁抗洪能力评估和水害预报提供依据。研究结果表明:基于反弯点简化的三角形单位线法理论清晰,模型简单,模型参数确定方便,计算结果精度满足工程要求,过程易于桥梁专业技术人员掌握。
Taking flow calculation of bridges in small and medium watersheds lacking hydrological data as the research object, a triangle unit hydrograph method based on points of inflection simplification of instantaneous unit hydrograph is present. Through the shape comparison of instantaneous unit hydrograph and simplified triangle unit hydrograph, triangle unit hydrograph method for bridges flow calculation based on points of inflection simplification is put forward. Triangle unit hydrograph model is established, and mathematical formulas of rising time, retreating time and peak value are deduced. Based to the theory of influence line loading, the surface runoffs produced by design (check) storm or real-time storm is calculated by loading design (check) rainfall series or real-time rainfall series on triangle unit hydrograph model. Calculation results can provide theoretical basis for design flow calculation of newly built bridges, flood prevention capability assessment and flood forecast of existing bridges. It is found that the triangle unit hydrograph method based on points of inflection simplification is easy to defermine because of its clear theory and simple model parameters. Also, the calculation accuracy can satisfy the engineering demand. It is easy for professionals to master this calcuation process