| In recent years,with the rapid development of rail transit construction in China,the cases of new subway tunnels crossing existing high-speed railway bridges are increasing.Most subway tunnels are constructed by mining method or shield method.There are differences between these two forms of subway tunnels in terms of construction characteristics,control measures,and the impact on high-speed railway bridges in the construction and operation stages.However,existing research lacks analysis of such differences.Therefore,relying on a mining method and shield method of subway tunnels side through a high-speed railway bridge project,numerical simulation and field measurement are combined.Firstly,the simulation model is established by ANSYS finite element software.By adjusting various construction factors such as reinforcement scheme and construction method,the construction process of subway tunnel under various working conditions is simulated.The engineering monitoring data are compared with the numerical simulation results to verify the accuracy of the model calculation and summarize the deformation law of the high-speed railway bridge.At the same time,ABAQUS finite element software is used to establish the simulation model.By setting different situations of subway and high-speed rail train operation,the operation process of subway tunnels under various working conditions is simulated,and the deformation and vibration law of the high-speed rail bridge is summarized.The main research results are as follows:(1)Tunnel excavation was carried out according to different reinforcement schemes.The order of the vertical deformation peak values of the adjacent surface,pier column and ballast bed of the new mining method tunnel is as follows: nonreinforcement > isolation pile > surface pre-grouting > isolation pile and surface and grouting.The new shield tunnel is: no reinforcement > isolation piles.This shows that isolation pile layout and surface pre-grouting can effectively reduce the deformation impact of tunnel construction on the high-speed railway bridge.(2)According to the existing reinforcement scheme,different mine construction methods were used to excavate the tunnel.The order of influence degree on the adjacent surface,pier column and roadbed is as follows: upper and lower bench method > CD method > CRD method.(3)By comparing the data of manual monitoring and numerical simulation,the peak deviation rates of vertical and lateral deformation of pier columns in the process of new shield tunnel crossing are 8.2% and 3.8%,respectively.The overall trend and peak position of deformation are consistent.It can be seen that the numerical simulation results well reflected the deformation effect caused by actual tunnel crossing.(4)In the case of isolation piles,the relationship between the peak values of the vertical deformation of the surface,pier column and roadbed caused by tunnel excavation is: mine tunnel construction > shield tunnel construction.It can be seen that for this project,under the same reinforcement measures,the influence of tunnel excavation at the construction site of the mine tunnel on the deformation of the surface and the existing high-speed railway bridge structure is greater than that of the shield tunnel construction site.(5)Under the condition of only running high-speed railway,the peak values of the dynamic responses of the bridge,track and train are smaller than those under the condition of three-vehicle intersection.This shows that the open operation of subway tunnel has little effect on the use of the upper high-speed railway bridge and the safe operation of high-speed railway trains.(6)The peak values of each dynamic response of the high-speed railway bridge,track and train passing through the high-speed railway bridge site by the mine-based subway tunnel are less than or equal to that of the shield-based subway tunnel passing through the high-speed railway bridge site.The smaller the peak values of each dynamic response are,the safer the driving is. |
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