Impacts Of Bridge-Pier Types On Ice Jams Evolutions:An Experimental Study

Ice jam is a common ice phenomenon in rivers in high latitudes area.The bridge piers change the boundary conditions of natural rivers,which reduce the effective water-crossing area of the section where the piers are located,and affect the ice transport near the piers,so the evolution of ice jams become more complex.The pier type(pier type is classified according to plane shape)also changes the river boundary conditions,which has a certain impact on the evolution and development of ice jam.Through the experimental study of pier type on the evolution and development of ice jam,it can provide some reference for ice prevention and disaster reduction.Through flume tests,the present studies the effects of four pier types on ice jam accumulation and backwater change.The experimental results show that pier type will affect the accumulation order of ice jams.The second and third accumulation of tip-shaped pier and rectangular pier are relatively small.The sequence of initial ice jam thickness near the pier generally is rectangular pier,tip-shaped pier,Round end-shaped pier and cylindrical pier from large to small,while the balance ice jam thickness presents the law completely opposite to the initial ice jam thickness.The increment of ice jam water level always keeps rising before reaching the equilibrium stage.The backwater process generally presents the characteristics of slow first and then fast.In the equilibrium stage,the water level basically no longer changes.The sequence of backwater height due to ice jam is the tip-shaped pier,rectangular pier,Round end-shaped pier,cylindrical pier from large to small.In addition,through the analysis of various factors,the expression of balanced ice jam water level increment considering the influence of pier type is given.