Research On Construction Monitoring Of Long-span Prestressed Concrete Continuous Girder Bridge For High-speed Railway

At present,the long-span prestressed concrete continuous girder bridge has been widely used in highway,urban and railway bridge engineering.The main reason is that this type of bridge has balanced force,stable structure,large safety degree,and good wind resistance and earthquake resistance.Long span prestressed concrete continuous girder Bridges are usually constructed by hanging basket cantilever casting.During construction,the alignment and stress of Bridges are affected by many factors,such as concrete bulk density,tension control stress,channel friction coefficient,channel deviation coefficient and so on.In order to ensure that the structural stress of the bridge is always controlled within the allowable range and the alignment of the bridge structure meets the design requirements,it is necessary to accurately control the construction process of continuous girder bridge.Based on the continuous beam bridge construction of Wangyu River Bridge across 204 National Highway（70+125+70）m of Nanyanjiang Intercity railway,this paper studies the key techniques and construction monitoring of cantilever construction of long span prestressed concrete continuous beam bridge of high speed railway.The main contents are as follows:（1）Midas/Civil finite element software is used to establish the construction simulation model of long-span prestressed concrete continuous girder bridge,the key construction technology and construction scheme are studied,and the common theoretical methods in construction control are described.（2）in view of the continuous girder bridge in vitro temporary consolidation,based on the finite element model for the main girder suspension pouring construction force for precise analysis,considering the factors such as prestress,shrinkage and creep influence on temporary consolidation stress,analyzes the temporary rigid fixity changes to the structure of steel tube longitudinal spacing,for similar projects of temporary consolidation design provides a new way of thinking.（3）Based on the finite element simulation model,the stress and displacement of continuous girder bridge in different construction stages are analyzed;At the same time,the influence of construction parameters（concrete bulk density,tension control stress,friction coefficient and deviation coefficient）on deflection of continuous girder bridge in each construction stage is analyzed.（4）The RBF neural network was constructed by taking the stress data calculated from the finite element model of continuous beam bridge as input samples and the main beam parameters（concrete bulk density and tension control stress）as output samples,and the MATLAB software platform was used to complete the network realization and training.Input the real value for feedback analysis,obtained more close to the actual construction state of the main beam parameters,the finite element model parameters correction,better guide the subsequent beam construction.（5）The displacement and stress in the construction process of the main beam are measured in real time,and the corresponding theoretical data are obtained by using the modified finite element model of continuous beam bridge,and the pre-camber and elevation of the vertical mold are corrected in real time to achieve accurate control of the main beam alignment;By comparing and analyzing the difference between the measured stress value and the theoretical stress value,the stress of the main beam is always controlled within the safe range.