Study On Construction Technology Of Jiangyou Fujiang River Grand Bridge

As an indispensable part of traffic construction,prestressed concrete continuous girder bridge has been rapidly developed in recent years.In the range of 40~150m span,prestressed concrete is considered from the perspective of structural stress characteristics and economy.Continuous beam bridges have become one of the most desirable bridge types.During the cantilever construction of prestressed concrete continuous beams,the control of the linear shape is very important.The reasonable setting of the pre-camber is to ensure that the bridge is smooth and consistent with the design line shape.However,there are still many uncertain factors in the actual construction,which bring great difficulty to the pre-camber control,such as concrete bulk density,concrete elastic modulus,prestress loss,concrete shrinkage and creep,etc.Therefore,in the construction process,the final formation is guaranteed.The shape of the bridge line and the control of the pre-camber of the construction are very important.The paper optimizes and analyzes the key technologies and special construction schemes of the construction of the Jiangyou Hanjiang River Bridge.Based on the current construction technology and experience,the paper discusses the construction technology of the prestressed concrete continuous beam bridge and the factors affecting the pre-camber of the main bridge.Conduct finite element analysis and propose corresponding countermeasures.The main research contents are as follows:(1)From the perspective of actual construction,it analyzes the characteristics of control engineering and difficult and difficult projects,and focuses on the construction techniques and solutions for the construction of water piers and continuous beams,including:engineering overview,hydrogeology,technical standards,control engineering and heavy and difficult projects,and construction The problems that may be encountered in the proposed solutions;(2)According to the existing design specifications and drawings,the design parameters of prestressed concrete continuous girder bridges are drawn.The finite element analysis software Midas/Civil is used to establish the calculation model,and the concrete bulk density(2%,5% and 10% increase and decrease)and elastic modulus are respectively taken.(2%,5%,and 10% increase or decrease),pouring days(3,4,5,7d),discuss the impact of parameter changes on the construction pre-camber.The analysis results show that the maximum pre-camber increment is-7.06 mm,which is 8.26% of the initial pre-camber of the corresponding node,and the maximum increment is 7.16 mm,accounting for 8.38%.Whenthe amount is reduced,the maximum value of the pre-camber increment is 4.22 mm,which accounts for 4.94% of the initial pre-camber of the corresponding node,and the maximum increment of the elastic modulus is-3.77 mm,accounting for 3.94%;the number of pouring days is 3d.When increasing to 4,5,and 7d,the maximum increment of pre-camber is-1.91,accounting for 2.23% of the initial pre-camber of the corresponding node.Therefore,in the actual construction,the material parameters should be measured and analyzed to reduce the deviation of concrete bulk density and elastic modulus,and the number of pouring days should be strictly controlled to ensure the effective setting of pre-camber and the safe construction of bridge structure.(3)The various factors affecting the pre-cavity of the cantilever casting method and the pre-camber of the bridge are described,including the dead load,prestress,system conversion,basket deformation,shrinkage and creep,etc.during the construction phase and the prestress loss in the bridge stage.1/2 live load and shrinkage and creep in the operation stage,etc.,and propose effective control measures for the influencing factors of different stages.