Research On The Flow And Scour Characteristics Of The Skew Bridge At The Downstream Of The River Bend

Influence of bridge construction on river channel become great complexity due to the effect of river natural statuses,incoming flow conditions,bridge structures,bridge locations,and many other effects,which is difficult to study from theory completely. Judging from the current situation,the research of flow patterns,backwater,and pier scour after the project of the skew bridge was not in-depth,which needs to carry out further systematic experiments as well as theoretical analysis,and the river model test method is the best shortcut.River model test can display the evolution of natural river successfully,and be able to accurately predict the evolution tendency of river bed after the project,ascertain both the level of the backwater and the bridge local scour depth at the same time,which could be a technical support for relevant administration and engineering design.Taking one river model test as an example,this article details its design method, meanwhile various engineering schemes are carried out.In this river model test the flow pattern,the level of the backwater and the bridge local scour depth were measured under different conditions.Then the results of the backwater level and the bridge local scour in different diameter,bridge span and various river-bridge skew angles were compared.Analyzing experimental data of the river model test,some results were as follows. At the downstream of the river bend,when the discharge hydrographs are the same,the level of the backwater and the depth of bridge local scour for the large-span piers are less than the small cylindrical piers with the same river-bridge obliquity.The smaller the obliquity of the river-bridge are,the more serious of the backwater level and the bigger depth of bridge local scour increased by the same piers are,moreover it also had strongly influence on river bed evolution.In addition,the small river-bridge obliquity study showed that the water surface slope of the left and right bank aroused by the existence of the river bend was reduced as the result of construction of project.Given the test results,it is necessary to increase the depth of foundation,enhance the safety factor,and reinforce the embankment at the downstream to ensure the operation of the project safely.In all,this will be an important reference for other river model tests.And these conclusions will also enrich and perfect theoretical results of the backwater and the bridge local scour.