The Analysis And Safety Control Research Of Long-span Steel Box Arch Bridge During Push Construction

At present,with the continuous development of China’s transportation construction,bridge construction has also made rapid progress,and steel box arch bridge has been promoted and applied for its beautiful appearance,large span,light structure and other characteristics.For long-span steel box arch bridge,pushing construction method is a common construction method,especially in the construction of crossing river,canyon and existing line.There are many construction stages in the process of pushing construction of long-span steel box arch bridge,and the stress situation is complex.It is necessary to study the construction process of long-span steel box arch bridge and analyze the key problems in the construction process.Based on the 1-112 m six line simply supported steel box composite arch bridge of Fengtai super large bridge in the reconstruction project of Fengtai station in Beijing,this paper simulates the process of pushing construction,and studies the overall force,local structure safety and safety monitoring of pushing construction.The main research contents and completed work are as follows:(1)The principle,characteristics and safety control contents of jacking construction technology are summarized.The multi-point jacking construction method and research significance used in this project are emphasized.(2)This paper introduces the general situation of the bridge engineering,and uses Midas civil finite element software to simulate the whole jacking process of the bridge,studies the overall force and deformation of the bridge in the jacking process,and studies the reaction of the temporary pier in each construction stage.The simulation results can be used as the basis for construction monitoring.(3)Through the simulation model,the force and stability of the temporary pier in the process of launching are studied,and the influence of the uneven vertical deformation of the temporary pier under the most unfavorable conditions of bridge construction is studied,which provides a theoretical basis for the settlement limit of the temporary pier in the construction monitoring.At the same time,this paper puts forward a kind of reverse preloading method,which is used in practical engineering,and effectively eliminates the uneven settlement of temporary pier.This method can provide reference for similar projects.(4)By studying the force and stability of the rigid suspender of the bridge,this paper puts forward a measure to enhance the stability of the rigid suspender,which effectively enhances the stability of the bridge in the process of pushing,and ensures the smooth progress of the pushing process.(5)Based on the model calculation results and structural safety research results,the stress and deformation of each component in the whole bridge jacking process are monitored in real time,the settlement of temporary pier and the lateral deviation of bridge longitudinal axis are monitored in real time,and the monitoring situation is analyzed to control the safe completion of bridge jacking construction.