Force Analysis And Engineering Application Of Long-span Steel Concrete Curved Bridge During Incremental Launching Method Construction

Since reform and opening up,the rapid development of highway traffic in our country,urban traffic is now quite rich,remote mountainous area highway construction is consummates our country an important part of highway network to promote regional harmonious development,in some remote mountain area in our country,the construction of the bridge is affected by many geographical environment,such as in the construction process of construction of precast floor space is limited,the work high above the disadvantageous factors lead to some traditional construction technology already can not meet the requirement of the construction of specific environment,especially the location in the middle of the mountain across the valley bridge,and many of the characteristics of steel box girder jacking construction technology happen to comply with the requirement of the construction of the geographical environment,It has very important research value to the construction under some special conditions such as mountain area.The construction of a bridge on Xiangli Expressway in Yunnan Province was carried out in July 2019.The bridge was constructed by off-site prefabrication,transportation,on-site assembly,and then the construction was carried out by using walking jacking technology.As the maximum jacking span in the middle span,up to 70 m,the structure of the guide beam deforms greatly when the pier of the guide beam is carried out,so the jacking construction cannot be successfully piered at one time.In this paper,taking it as an example,the theoretical analysis and numerical simulation are used to analyze and verify the construction process,the heavy and difficult points in the construction process,and the overall stress of the structure in each important stage of the jacking construction process,and the rule of how to optimize the local design parameters is summarized.The research results of this paper are as follows:1st.through field investigation and study and access to data,it is understood that this jacking method construction belongs to walking multi-point synchronous jacking construction,and each stage of the whole jacking process is divided,which provides basic data and technical explanation for force analysis,calculation and evaluation in the subsequent jacking construction process.2nd.in order to analyze the force in the jacking construction,Midas/Civil finite element software was used to simulate and analyze each stage of jacking,and the following conclusions were drawn:(1)Through the analysis of finite element simulation results,the worst stage of the jacking method construction force is obtained,and after the optimization analysis,the worst stage appears in the same position,and it is concluded that the most unfavorable working condition in the course of jacking is generally the maximum stage of the overall structure cantilever in the course of jacking.(2)the stress of the jacking construction process to introduce by a temporary pier cantilever,the stress of the whole structure into linear change,vertical deflection,stress reaction,than numerical peak,the overall structure of the bearing capacity of the worst,after pushing down a temporary pier,the whole structure of vertical deflection,stress reaction,than numerical fell sharply,the structure bearing capacity to reach steady state.(3)because the bridge span is big,in the course of pushing the overall structure of the vertical deflection is larger,the deformation of the largest position in guide beam front,stiffness,self-respecting need when the design,optimization,can be used by changing the guide beam material,web flange plate,plate,web plate thickness increase stiffness,according to the design guide beam length for the largest span 0.6 ～ 0.7 times,weight can be changed by controlling the length.(4)When the basic design parameters are determined,the local optimization of the design parameters is carried out after the force analysis in the jacking construction stage,which improves the mechanical stability of the bridge to a certain extent.Therefore,it can be seen that this method can better guarantee the safety of the construction process and the mechanical stability of the whole structure.3rd.through a comprehensive understanding of the jacking construction technology and the finite element calculation and analysis of each stage in the jacking construction process,the key construction problems in the construction process are summarized,and the control measures for the construction difficulties and difficulties are provided,which can provide some reference for the practical projects of the same type.