Barrier Analysis Of Transverse Pushing And Synchronous Control Of Steel Box Girder Of Railway Multi-Span Continuous Turnout

With the increasing railway passenger traffic,some existing bridges can no longer meet the passenger demand,so it is necessary to rebuild and upgrade the existing bridges.However,the transverse incremental launching method can be used to upgrade the existing railway bridge,and the existing beam can be rebuilt during the skylight period without disturbing the line traffic,which has the characteristics of short construction period and simple construction process,and can effectively reduce the impact on the structures under the bridge.Based on the beam replacement project of Jin Ke Qiao Avenue Station in Shaoxing Intercity Railway Phase II project,this paper compares two schemes of jack-slideway and slider-slideway in transverse pushing,and analyzes and studies the distribution law of supporting reaction,local stress state of beam during construction,synchronous control strategy of transverse pushing and optimization of rectification measures.The specific contents are as follows:(1)Based on midas model of continuous steel box girder of turnout,the distribution of supporting reaction force,anti-overturning coefficient of section and jacking time under static state,jacking state,jacking state and termination state are calculated and compared,and it is clear that the jack-slide scheme can meet the requirements well;It is found that when the slideway sinks,its own supporting reaction will decrease,and the supporting reaction of both slideways will increase accordingly,and the closer the slideway is to the settling slideway,the greater the supporting reaction will bear.(2)The beam-shell-solid multi-scale models of steel box girder under three jacking conditions are established,and the local stresses in the contact areas of beam-3D jack and beam-lateral jack during lateral jacking are analyzed,and the main factors affecting the local stresses are analyzed,and the following conclusions are drawn: the maximum stress of continuous steel box girder in the most unfavorable jacking state is 94.93 MPa,which is far less than the allowable stress value of 210 MPa.The difference of differential settlement between the two jacks should be controlled within 1mm,and the difference of top elevation should be controlled within 2mm,which can effectively avoid the stress concentration of the beam;The elevation difference between No.4 slide and No.3 slide should be controlled within 2mm,while the elevation difference between No.5 slide which is relatively close should be controlled within 0.5mm.(3)Aiming at the problem of unsynchronized jacking in the process of beam jacking,the influencing factors of synchronization(jacking force deviation,slideway elevation deviation and jacking speed deviation)are analyzed,and it is concluded that the deviation of preset jacking force and friction force of each slideway should be less than 5%,and the monitoring interval of steel box girder displacement should be less than 45 s in the process of jacking,so as to avoid excessive axis deviation in the process of jacking,which will lead to damage or even overturning of steel box girder;The elevation difference between jacks is controlled within 2mm,which is helpful to balance the jacking force and friction force;When the lateral deflection of steel box girder is controlled within 40 mm under different axial deflection forms,it has little influence on the stress and stability of the girder;The jacking distance has less influence on synchronization,but more on its jacking construction time,and the jacking speed has greater influence on synchronization.In jacking,the difference between the actual jacking speed and the preset jacking speed should be less than 0.2 mm/s.(4)According to the problems of stress concentration of beam,axis deviation and unsynchronized jack-up analyzed above,the monitoring scheme of various parameters in the jacking process is preliminarily determined,the engineering guiding measures and lateral deviation treatment measures applied in the jacking process are integrated,and the rectification measures are optimized in combination with the jacking deviation analysis mentioned above,so that accurate rectification can be realized in the jacking process.