Study On Deformation Of High-speed Railway Shield Tunnels By Close Excavation Of Urban Rail

In China,there have been some adjacent high-speed railway projects.In the construction process of these projects,there are a series of technical problems,such as high-speed railway deformation control standards,risk management of adjacent high-speed railway projects,adjacent high-speed railway deformation prediction,deformation monitoring methods,adjacent high-speed railway deformation control technology and so on.Among them,it is one of the hot issues to study the settlement and deformation of the largediameter shield tunnel adjacent to the urban rail excavation project,which is of great significance to the safety construction of the adjacent high-speed railway project and the safety of the large-diameter shield tunnel of the high-speed railway.In this paper,the deformation law of the track and tunnel structure in the large-diameter shield tunnel of high-speed railway caused by the construction of the adjacent project is studied through the mutual confirmation of the theory,numerical simulation and monitoring data.Based on the finite element analysis,the influence of the material properties of the soil layer where the high-speed railway tunnel is located,the grouting material properties on the deformation of the high-speed railway tunnel and the deformation control measures of the adjacent project are studied.The main research contents and results are as follows:(1)Based on the study of the influence mechanism of the adjacent project on the highspeed railway tunnel,a three-dimensional spatial coupling model of the adjacent project surrounding rock existing high-speed railway tunnel and track is established.The lateral deformation law of the stratum,the deformation mechanism of the high-speed railway tunnel and the deformation mechanism of the high-speed railway track under the construction of the concealed excavation adjacent project are analyzed,which provides a theoretical basis for the subsequent finite element analysis.(2)Based on the mining method of Dazhongsi-Jimenqiao section tunnel of Beijing Metro Line 12 passing through Qinghuayuan shield tunnel of Beijing-Zhangjiakou high speed railway,the nonlinear finite element software ABAQUS is used In 2016,Combined with the field monitoring data and the derived formula of the ground settlement caused by the excavation of the ellipse simplified section of the double line parallel tunnel by the random medium method,the deformation response of high-speed railway shield tunnel,prefabricated inverted arch and ballastless track under the reinforcement of advanced large pipe shed and deep hole grouting is analyzed.The error is 8.9% compared with the monitoring data,and the peak error is 2.4% compared with the random medium method,which proves the relative accuracy of the calculation results.(3)From the perspective of vertical displacement,the surface settlement has the characteristics of peck curve.With the progress of construction,the peak value first moves from the center of the high-speed railway tunnel to the excavation of the right metro line,and then to the excavation of the left metro line.At this time,the surface settlement reaches the maximum value.Finally,return to the center of the HSR tunnel.Shield tunnel,precast invert and ballastless track represented by rail also have similar deformation laws.From the perspective of horizontal displacement,the horizontal displacement of the ground surface and the center of the prefabricated inverted arch is in the shape of "several" in the stage of track laying,excavation of the right line to the lower part of the high-speed railway tunnel and excavation of the left line to the lower part of the high-speed railway tunnel,and the horizontal displacement of the soil mass above the center of the highspeed railway tunnel,the center axis of the right line of the subway and the center axis of the left line of the subway successively reaches the maximum value,which is approximately zero at the end of construction;However,the horizontal displacement shape at the horizontal diameter of the shield tunnel shows the similar characteristics of vertical displacement,the difference is that the displacement direction is horizontally pointing to the excavation direction;the horizontal displacement of each rail of the double track of high-speed railway is relatively complex: in the stage of laying the track,the left and right rails of high-speed railway move in the opposite direction.(4)This paper studies the influence of soil elastic modulus,cohesive force,Poisson's ratio,internal friction angle,cohesive force and elastic modulus of grouting material on shield tunnel of high-speed railway caused by the construction of concealed excavation and close connection project,which can provide reference for similar construction of concealed excavation and close connection project.There are 111 pictures,21 tables and 69 references.