Study And Practice On The Cantilever Construction Control Technology Of (72+128+72) M For Zhengwan High-Speed Railway

With the continuous development of China's transportation industry,the requirements to the ability of a bridge to overcome obstacles are getting higher and higher.Long-span prestressed concrete continuous girder bridges have emerged as the times require,and their span is also increasing.Starting from the characteristics of this kind of continuous girder bridge,the span is large,the construction process is complex,and the main girder needs to undergo the process of system transformation before the completion of the bridge.These factors will have an impact on the alignment and stress of the girder.Therefore,it is crucial to ensure that the internal force state and geometric alignment of the main girder meet the design requirements through construction control during the construction of the girder.Firstly,this paper introduces the development status of construction monitoring technology at home and abroad,and expounds the necessity of construction control.Taking the construction monitoring project of Zhengzhou-Wanzhou high-speed railway(72+128+72)m continuous beam as an example,the structure of long-span continuous beam bridge is analyzed and studied;the finite element model of the whole bridge is established by using MIDAS/Civil finite element analysis software to simulate the construction stages of the bridge,and the simulation analysis is carried out;Analysis and calculation of cast-in-place support and temporary consolidation of piers and beams in section 0 of main girder are carried out;The finite element analysis software MIDAS/FEA is used to establish the solid model of section 0 of the beam body.The temperature and stress fields of the two construction schemes of integral pouring and layered pouring of section 0 of the continuous beam are analyzed,and the appropriate construction scheme is selected.Finally,according to the analysis data,the construction control scheme is formulated.The corresponding elevation measuring points,the buried stress sensors are arranged by the construction control scheme,and the deflection and stress of the beam body at each construction stage are measured accurately and timely.The deflection and stress of the beam body are compared with the theoretical model,and the errors are found and eliminated in time to ensure the smooth closure of the continuous beam and the completion state of the bridge meets the design requirements.