Research And Application Of Surveying And Setting Technology Of High-speed Railway Track Control Network On Main Girder Of Long-span Cable-stayed Bridge

With the continuous development of high-speed railway construction,it is an inevitable trend to lay ballastless tracks on the main beams of long-span cable-stayed bridges,but the structure of long-span cable-stayed bridges is complicated,and the structure of the main girder is affected by environmental factors such as temperature and load.The large deformation caused the multi-value problem of the three-dimensional coordinates of the CPⅢ points on the main beam,which made it impossible to lay the ballastless track on the main beam during construction and repair the track on the main beam during operation.In view of the above problems,this paper studies the method of setting out the ballastless track control network on the main beam of the long-span cable-stayed bridge,aiming to solve the multivalued problem of the CPⅢ control network on its main beam.mainly including the following research contents:(1)In view of the structural deformation characteristics of the long-span cable-stayed bridge,this thesis studies the layout method of each CPⅢ point on the main beam and the static deformation monitoring experiment method of the three-dimensional coordinates of each CPⅢ point on the main beam,including the longitudinal deformation of the main beam and the beam body and air Design method of temperature automatic monitoring system,experimental measurement method of plane and vertical deformation monitoring of each CPⅢ point on main beam.Combined with the experimental data,the change rule of the three-dimensional coordinates of each CPⅢ point on the main beam is analyzed;(2)This thesis studies the relationship between the change of the plane coordinate of each CPⅢ point on the main beam of the long-span cable-stayed bridge and its position and the reading of the longitudinal displacement sensor are studied.Then,based on this,the CPⅢ point real-time plane coordinate prediction model based on distance weighting was established,and the accuracy of the prediction model;(3)This thesis studies the linear relationship between the elevation change of each CPⅢ point on the mid-span of the main beam of the long-span cable-stayed bridge and the elevation change of the CPⅢ point on the mid-span.Then,the principal component regression method is used to extract the principal components that affect the CPⅢ point-to-elevation change of the mid-span,and a multiple linear regression equation is established between the various sensor reading changes and the CPⅢ point-to-elevation change of the main beam span.The real-time elevation prediction model of each CPⅢ point on the mid-span of the main beam is obtained,and finally the prediction accuracy of the model is verified;(4)Because the real-time plane coordinates and elevation prediction models of each CPⅢ point on the main beam of the long-span cable-stayed bridge are built on the basis of the static deformation monitoring data and various sensor data of the CPⅢ points collected in a certain period of time,their applicability exists certain limitations.To ensure the accuracy of the prediction model,static deformation monitoring experiments of 36 to 48 hours need to be carried out at intervals and in different seasons.After the high-speed rail is put into operation,only the skylight period can go online for measurement operations,and it does not have the conditions for conducting static deformation monitoring experiments.In order to ensure the smooth progress of the linear retesting of the ballastless track on the main beam of the high-speed railway long-span cable-stayed bridge during the operation period,this paper combines a large-span cable-stayed bridge project with a free station-based survey method the method of quickly obtaining the real-time three-dimensional coordinates of each CPⅢ point on the main beam of the long-span cable-stayed bridge by polar coordinate measurement method,and the accuracy and feasibility of this method are discussed.