Study On Simplified Construction Technology And Deformation Characteristics Of Small Span Frame Bridge Through Railway

With the continuous construction of roads,it is inevitable to cross railway,how to ensure the safety of the train has become a prominent research topic.In this paper,through a large number of documents and field investigation,the influence of the construction of the small span box under the railway on the subgrade and the deformation are studied and discussed.Based on Xiakeng No.1 underpass Zhanglong railway project in Fengcheng street,Yongding District,Longyan City,this paper determines the monitoring plan on the basis of the existing construction plan,establishes the monitoring platform based on BIM Technology,discusses the deformation characteristics of the box underpass ordinary speed railway,carries out analytical calculation and numerical simulation based on the actual monitoring data,and explores the effect of support pile construction on the subgrade Influence and deformation law of reinforcement system under dynamic load of train.The main work is as follows:(1)Based on the analysis of the design data and construction scheme of frame bridge jacking,combined with the previous engineering examples and the existing environment,the monitoring scheme is determined,and the field monitoring is carried out;(2)The intelligent monitoring platform based on BIM Technology is established to realize the all-weather and all-time automatic collection of monitoring data.The visibility of BIM is used to realize the visualization and dynamic display of monitoring data.Through the establishment of comprehensive early warning system,the timely and effective transmission of early warning information is realized.Through nonlinear regression analysis,the change trend of monitoring data is predicted to ensure the jacking construction Operation safety of existing lines;(3)The deformation characteristics of the subgrade and the reinforcement system under the dynamic load of the train during the excavation of the supporting pile are discussed respectively,and compared with the actual monitoring data,the reliability of the numerical calculation is verified;(4)Three basic principles of the deformation control standard of the railway under the frame bridge are determined.On the premise of ensuring the track smoothness,according to the relevant specifications and deformation characteristics analysis,the early warning value and alarm value of seven items are determined through mathematical calculation,and the safety analysis of the deformation of the reinforced structure is carried out according to the determined control value;(5)Under the premise of safety,the parameters of pile diameter of support pile and trainspeed are optimized.It is found that when the train speed is increased from 45km/h to 60km/h,the vertical acceleration value of D24 temporary beam increases by 19.7%,which is a big increase.For the safety of train passing,it is recommended to limit the speed of 45km/h when strengthening the structure.