Study On The Influence Of Parallel And Deep Foundation Pits Excavation On Existing Subway Stations

With the rapid development of Chinese economy and the increasing of urban ground transportation pressure,subway construction has become an important way of developing and utilizing underground space.However due to the decreasing of available urban land resources,more and more excavation engineerings are adjacent to the completed subway station,and the construction of the post construction project will certainly have an impact on the first construction project.In order to deeply and comprehensively study the influence of parallel and deep foundation pit excavation on nearby existing subway stations,On the basis of domestic and international research,the internal force and deformation characteristics of subway station caused by deep foundation pit excavation are systematically studied by means of numerical simulation and field test on the background of deep foundation pit project of Changsha Metro.Based on the load-structure method and combined with the open-cut method and Segment of Cover-excavation Reverse Operation of the station foundation pit,the excavation and support construction of the deep foundation pit in the equipment area are simulated by the finite element software modeling and calculation.In the light of two main conditions of no water and full water,the bending moment,shear force,axial force and displacement under the different excavation depth are comprehensively analyzed.Actual process of the construction combined with the specific project example was analyzed by three-dimensional finite element analysis software.In view of the construction stage,the influence of the excavation of the parallel and deep foundation pit on the existing subway station structure was analyzed thoroughly,and the variation law of the internal force and displacement of the model under different excavation depth were also studied.Taking the deep foundation pit project adjacent to the existing subway station as the research object,combined with field monitoring test,the monitoring data of the construction process was analyzed.The change of deep horizontal displacement of retaining structure of foundation pit was obtained,and the variation law of horizontal deformation of subway station structure with the excavation depth and time was discussed.Combined with the deep foundation pit project adjacent to the existing subway station,the specific limit of allowable deformation of metro station structure was obtained.According to the foundation pit deformation and its development,transfer and target building(structure)protection and other aspects of the building,the deformation control technology of deep foundation pit under complicated environment condition was analyzed,and the "source control,process control,path partition,objects of protection" integrated control concept was also put forward,which forms a deep pit deformation control technology system.