Physical Model Studv Of Influence Of Different Pile Numbers On Local Scouring Of Bridge Piers

With the development of national strategic regional planning on the theme of marine economy,the number of offshore highway projects is increasing.The construction can meet the needs of strengthening the transportation links between islands,improving the layout of road networks and road networks in central urban areas,alleviating urban traffic pressure,and speeding up construction.And marine economic development are of great significance.During the construction and operation of a sea-crossing bridge,scouring of the pier is one of the main factors leading to water damage to the bridge.Determining the scouring depth of the pier is also a prerequisite for designing the buried depth of the pier foundation,which is of great significance in the life cycle of the bridge.Based on a bridge project in Zhoushan,Zhejiang Province,this paper takes single-pile bridge piers and group pile piers as examples to analyze the influencing factors and mechanism of local erosion.Compared with single pile foundation,multi-pile and group pile foundations have more influencing factors.For single piles,the flow impact is only a single foundation;while for multiple piles and group piles,the impact of the flow impact is also affected by the interaction between each single pile.The influencing factors are more complicated than the single pile foundation.The empirical formula is Applicability is limited under the combined effect.The current empirical formula of local scouring of bridge piers is theoretically analyzed,and the best is selected.At the same time,the physical model of the pier scour test is carried out,and the scale of the model is determined according to the similarity criterion;by analyzing the characteristics of the sediment sample in the pier area,the appropriate model sand is selected for the test;and the measurement points in the model area are reasonably controlled to ensure data collection Accuracy;analyze the hydrodynamics of the bridge pier area and the evolution of the seabed,simulate the tidal water flow through water level control and tidal current control,and conduct experiments using a combination of multiple working conditions.After the pier scour test is over,the data obtained from the test are compared with the empirical formula.In the case of partial scour of bridge piers with different pile numbers,the difference between the calculated value of the empirical formula and the test value is analyzed,and the actual scour depth is combined to obtain the final scour depth and analyze the factors that cause the difference.At the same time,suggestions for rationalization of scour protection measures for bridge pier are put forward.