Study On The Influence And Countermeasures Of The Construction Of Subway Tunnels Close On Existing Structures

In recent years,with the continuous improvement of urban underground transportation network,the construction of subway tunnel near the existing buildings is becoming increasingly prominent.There are many cases of subway tunnels passing through the roadside buildings,underground buried pipes and viaducts,existing tunnels or subway stations.During the construction process,the excavation and unloading of the soil will cause the change of the original stress state of the surrounding rock and soil mass during the construction process,resulting in certain displacement and deformation.Affected by the displacement and deformation of surrounding rock and soil mass,there will be some additional stresses,even serious damage,on the buildings' foundation,underground pipelines,viaduct foundations,interval tunnels and subway stations.Therefore,it is of great significance to study the influence of subway tunnel construction on adjacent buildings and structures.In this paper,taking the construction of Shenyang Metro Tunnel Line 9 the sixteen section as background,combine the method of field survey,data collection,collate domestic and foreign related research,numerical simulation and field measurement to study the ground settlement caused by the construction of subway tunnel,the construction of the subway tunnel close to the above the existing subway station,tunnel construction under the tramway and other related aspects.Here are the research results obtained:Considering the influence of soil property,thickness and tunnel span onstratum settlement caused by the tunnel construction,the expression of Peck formula in different buried depth strata is derived.Based on the basic principles of Peck method and stochastic medium theory,a finite element method is proposed to calculate the surface settlement of tunnel construction,which Both accuracy and computational simplicity.The slices method in the analysis of slope stability is introduced into the study of ground settlement and propose a method to calculate the formation settlement based on the slices method.(1)The influence of the construction of Shenyang Metro Line 9 pass through the existing the Olympic Sports Center subway station of the Metro Line 2 is studied and a reasonable arrangement and method for construction is obtained.In the construction of the tunnel through the existing station,deep hole grouting is helpful to reduce the settlement of the existing station and control the influence of the construction on the structure of the station.Applying lifting force to the bottom plate of the station can better control the settlement and deformation of the bottom plate of the station by using Jack lifting technology.Through numerical simulation analysis,the scheme of setting different initial lifting force on the Jack in different position is put forward.The scheme of initial lifting force arrangement suitable for this project is studied.The overall settlement of the station is controlled within 0.5 mm,which ensures the smooth construction of the tunnel and the safe operation of the existing stations.(2)In the construction of the pothole and cross gallery nearby the tramway,the scheme of pothole and cross gallery alternation construction is put forward.The scheme can ensure that the track settlement of tram is within the allowable range and is beneficial to control the deformation of the supporting structure.The construction of the tunnel by step method is convenient for rapid construction on the basis of controlling the settlement of the ground surface and tramway,so as to ensure the progress of the project.The prelude to the construction of underground engineering in China is about to be opened,and there are more and more projects to finish.Based on the engineering case,the typical working conditions for the construction of the subway tunnel near the existing buildings are studied and analyzed,and the construction effects and construction countermeasures are obtained.The relevant achievements of this paperhave guidance and reference for similar projects in the later period,which is beneficial to the development of underground space engineering in China.