The Influence Factors Of Local Scour Under Ice Cover-an Experimental Study

Both ice cover and ice jams occur frequently in northern rivers in the winter.The construction of the bridge in the flow changes the original hydraulic and boundary conditions,which results in local scour around the pier.The presence of ice cover has an effect on local scour around the piers.At present,although there are a lot of research achievements on local scour of bridge piers under open current,the research on local scour of bridge piers under ice sheet is very limited.Therefore,in this paper,under the condition of clean water scour,the influence of various factors on local scour around the pier is experimentally studied.Under the condition of clean water scour,the impact of ice cover,velocity and water depth on local scour around the pier was studied experimentally.The results show that the presence of ice cover leads to greater flow velocity and gradient of flow velocity near bed compared to open channel conditions.Therefore,the local maximum scour depth of the pier is greater.If the flow velocity or pier diameter increases,the local maximum scour depth becomes larger.If the water depth increases,the local maximum scour depth under ice cover becomes smaller.According to the experimental data,the formula for calculating the maximum local scour depth of the pier under the condition of ice cover is given,and the results are in good agreement with the experimental results in domestic and abroad.