Design Flood Of Medium And Small Watershed Bridges Of Hunan Province Based On Flow Influence Line Method

The washout of bridge is a major cause of bridge derogation, and the deficiency of flood in bridge design can directly cause the washout of bridge. So it is necessary to determine the flood flow very accurately to improve the flood capacity of the bridge. Nowadays, the flow of small and medium-sized bridge in china can be got according to the rainfall based on the actual situation of the bridge, by employing region empirical formula, rational formula, unit hydrograph method, and Railway Design Institute method etc.. But these methods are labor-intensive and difficult to collect data.According to the rainfall information from real-time monitoring network established by the meteorological department of Mainland-level city in Hunan Province in recent years and the rainfall receiving system of Beijing-Guangzhou Railway, Shanghai-Kunming line along the criss-cross railway hub in Hunan province, this thesis adopts line method, with the help of bridge flood design at home and abroad and Hunan traditional method of flood calculation in bridge design,to study the rainfall load, the corresponding flow influence line, and the application of the design flood of the special small and medium-sized basin bridge in Hunan Province.(1) Based on the theory of flow influence line method, the design flood rainfall in Hunan province is loaded along the line of flow influence, which enriches the calculation method in small and medium-sized basin bridge, and is more convenient for bridge engineer’s use. With the method of integrating mesoscale network of rainfall stations and historical flood pier or riparian water marks in calculation of the small and medium-sized basin bridge, the calculation accuracy is improved compared with the traditional methods.(2) Lots of researches are made on the rainfall load through influence line method of Hunan Province. The program is designed to calculate the design flood rainfall load. After determined the Reference drainage area, the paper draw the flow influence line in the area by means of the least squares method.(3) The method which employs rainfall to calculate the flood is applied. The number of parameters involved decreased and the impact from environment also gets smaller. The results show that the method is better than other traditional methods...