Study On Wave Force Of Double-wall Steel Cofferdam With Open Hole Under Wave Action

With the rapid development of coastal engineering and road engineering in China,more and more coastal cross-sea Bridges have been built.Due to the extremely complex Marine environment,the design and construction of the cofferdam are faced with challenges.Accurate calculation of the forces and moments acting on the cofferdam has become the key problem urgently needed to be solved in the bridge construction,which is related to the safety and reliability of the subsequent substructure construction.Most of the steel cofferdams for sea Bridges are in the form of circular,rectangular and round-end sections,and some projects are in the form of dumbbell sections.The Harbour Hydrological Code gives a calculation method for the wave force on the large scale circular cylinder in the ocean,but does not give any explanation for the calculation of the wave force on the cofferdam with openings in the outer wall.Therefore,it is very significant to study the wave suppression mechanism of the cofferdam with openings in the outer wall under the wave parameters.In this paper,circular cofferdams,round-ended steel cofferdam and rectangular cofferdams under wave load are the main research objects.The main contents are as follows:(1)Collect and sort out actual engineering data,including the beijing-shanghai high speed railway nanjing Yangtze river bridge of the Marine environment data and the size of the steel cofferdam construction information,mainly introduced the basic theory of wave,using the theory formula,standardization of formula and numerical simulation to solve large scale circular steel cofferdam in the rule under the action of linear wave by horizontal wave force and moment,all three are compared,and the deviation through correction of the model,get can accurately reflect cofferdam stress wave flume,and verify the Fluent software in this paper the accuracy of the numerical simulation method.(2)Built round,rounded shape and rectangle hole and don't open Kong Gang cofferdam model,calculation of open hole and not opening two steel cofferdam in the different parameters(double-wall spacing,relative water depth,wave steepness,diameter)of the horizontal wave force and moment,the introduction of the concept of reduction coefficient,mapping the reduction coefficient and the relationship between the factors and research the factors split hole cofferdam,the influence of the wave.(3)BP neural network was used to fit the relationship between the reduction coefficient and wave parameters such as the width of the surf face,fractional hole area,wave steepness and relative water depth.The accuracy of the relationship between the reduction coefficient and wave parameters was verified by taking three groups of different wave parameters.The calculation formula F=?F?0×K??d(F?0 is calculated by the rectangular standard formula,?is calculated by the reduction coefficient formula)is obtained,which has important reference value for further understanding of the wave elimination mechanism and wave force calculation of the steel cofferdam with external openings.