Research On Key Technology Of Cantilever Construction Control Of Long-span Continuous Beam Bridge In High-speed Railway

Cantilever pouring is a commonly used construction method for continuous beam bridge construction on prestressed concrete at this stage.For high-speed railways,the elevation of the bridge deck must be strictly controlled during the construction of the bridges due to the characteristics of the high-speed railway track structure and the strict requirements of high speed on the geometry of the track.Therefore,in the process of bridge construction,it is necessary not only to monitor and deal with the possible settlement of the pier and abutment,but also to control the height of the top of the grider in each stage.At the same time,due to the influence of various factors in the construction process and the transformation of the complex stress system in the cantilever construction process,the actual internal force and displacement of the bridge structure are different from the theoretical calculation values in each construction stage.Therefore,construction control must be carried out at all stages to ensure that the overall alignment and stress state of the bridge after closure will meet the design requirements.Firstly,the development of construction control technology for cantilever bridges was introduced in this paper,and then combined with the construction control of the New Canal Bridge of Lianyungang to Zhenjiang Railway,we studied the settlement observation and analysis of piers,the calculation and analysis of the support structure,and the strain and linear monitoring in the cantilever pouring process.The main work are as follows:1.This paper summarizes the research status and methods of construction control of cantilever continuous girder bridge,and analyzes the key factors of bridge construction control.2.The settlement observation points are laid on the bridge piers,and the elevation data of the observation points are periodically collected according to the requirements of the relevant specifications.By arranging the observation data,the curve of the settlement over time is plotted,and the settlement rule of the pier of the Canal Bridge during the construction period is summarized.Moreover,combined with the geological conditions of ground and the force form of pile foundation,the settlement rules of this kind of pile foundation is summarized under this geological condition,which provides technical support for the construction of the same basic type of bridge structure.3.In this paper,the mechanical properties of the support used in the construction process of the beam 0# block and Side span cast-in-place section are analyzed through the establishment of numerical model.By changing the structure of the tripod part in the upper part of the bracket,the force performance of the upper part is compared and analyzed,and the reasonable suggestions are put forward.4.The hanging basket used in cantilever construction is preloaded before construction,and the deformation measurement method is improved.At the same time,a full bridge numerical model is established to analyze the mechanical performance and alignment of the bridge at all stages of construction.5.The strain and elevation monitoring system of bridge is established to monitor the line shape and stress changes during the entire construction process of the bridge in real-time,and using the data obtained from numerical analysis to guide the bridge construction,finally,the effect of the control is analyzed after the bridge is completed.