Load A Series Of Studies Based On The Traffic Impact Line Method Of Guangdong Province, Bridges Conversion Rainfall

Bridge disaster by flood has caused a huge economic loss to our country. However, more than 80%of the middle-small-scale bridges in China have no hydrological observation stations at all, which has become an extrusive problem in transport and communications. Therefore, the studying of how to determine the design flow more effectively and find simpler and more effective ways of assessing the flood-resistant ability is a very important theoretic and applicable topic in middle-small-scale bridges.Estimates on the detection flow of middle-small-scale bridges still use the rainfall to calculate runoff, i.e. methods such as regional empirical formula method, reasoning formula method, unit hydrograph method, railway methods are used according to the practical situation of the bridge location. Parameters such as catchment area, slope of basin, length of main riverbed, hydraulic gradient, roughness are needed to define, which is labor-intensive and time-consuming, as well the collection of these datas is rather difficult.Based on domestic research on the flow influence line which is currently presented, the conversion rainfall load series appropriate for the flow influence line was proposed. VB program was used to draw out the conversion rainfall load series contour maps of Guangdong Province relative to the frequency of 1/100,1/50,1/25. The investigation of heights of water traces in the history of bridge piers was involved. Demarcating the flow influence line of the pier is to ensure the parameters. The design peak flow of corresponding frequency can be calculated when the conversion rainfall load series were impacted on the flow influence line.Datas through the site investigation of several bridges in Guangdong Province were researched as demonstration, which proves the creditability of this forecast method.The conversion rainfall load series contour map of Guangdong Province is straightforward and low time consuming. Data analysis through the site investigation suggest that the rainfall load series adopted from the conversion rainfall load series contour map can keep the error below 8 percent, compared with the one obtained by calculation of the synthetic unit hydrograph in Guangdong, which shows that the conversion rainfall load series contour map is of reliable precision.With the maximum rainfall according to this approach, there would be no need to confirm parameters of basin shape, catchment area, river length, slope of basin, etc, nor to check the design point precipitation and area precipitation.The pure rain process can be drew directly through the conversion rainfall load series contour maps of Guangdong Province, which can reduce a lot of work in checking the charts. Thus, it has more highly application value.