Research On The Existing Lines Deformation Law Of Multi-Section Box Culvert Under Railway Marshalling Station With Reversed Jacking Method

With the continuous improvement of our country's traffic network and the increasing number of highway and railway crossing projects,the construction of highway box culvert under railway can be widely used without interrupting the operation of the existing railway.The jacking construction of the box culvert will inevitably cause disturbance of the surrounding soil,resulting in the displacement and deformation of the surrounding soil,and then the deformation of the upper track structure.For box culvert under existing Line project,there was less research on the multi-section box culverts involved in jacking through the railway marshalling yard,but in the process of the box culvert passing through the railway marshalling yard,there were many existing railway tracks and contain the railway hump line in the process of the box culvert passing through the railway marshalling station.At the same time,the construction of box culverts with segmented sections is difficult,and the train can be installed.Further research was required in the construction area through the top of the box culvert.In this paper,the effect of multi-section box culvert on the existing railway subgrade and track under the top of the multi-section box culvert was studied.A three-dimensional model of soil-roadbed track strengthening structure was established,and the subgrade settlement and track deformation in the construction of multi-section box culvert were simulated and analyzed.The subgrade settlement and track deformation of the box culvert after each step was excavated at the top of the box culvert were simulated under the condition that the excavation step distance were 1 m,1.5 m and 2 m,respectively,so as to calculate the maximum settlement value and the settlement influence range of the subgrade and track under different excavation steps.The deformation law of subgrade and track caused by jacking of box culvert was analyzed.The roadbed settlement,track deformation and box culvert jacking deviation caused by actual construction was monitored on the basis of Tianjin Beihai Road entry Railway second Line jacking Bridge Project.According to the field monitoring data,this paper summarizes the rule of subgrade settlement and track deformation in the construction of box culvert through railway marshalling yard,and compares the monitoring data with the calculated results.The measured values of subgrade settlement and track deformation were in good agreement with the calculated results,which verifies the reliability of the calculated results.The law of horizontal deviation and elevation deviation in jacking process of box culvert can also be obtained from the monitoring data,which can be combined with box culvert deviation to analyze subgrade soil mass.And the internal relationship among the three was analyzed.According to the rules of subgrade settlement,track deformation and box culvert deviation,combined with the key construction links of box culvert through marshalling station,the excavation step,line reinforcement,jacking and rectifying deviation were obtained.In order to ensure the normal operation of the existing lines and the smooth advance of the box culvert,the paper puts forward the corresponding preventive measures and deformation control measures in the aspects of construction dewatering,so as to provide reference and reference for similar projects.