Analysis Of The Impact Of Shallow-buried And Under-excavated Tunnels In Subway Interchange Stations On The Surrounding Environment

The PBA construction method is a new construction method developed from the shallow burying and undercutting method.It has the advantages of effective control of ground deformation,high construction safety,strong construction flexibility,high section utilization,and low cost.It has been used in Beijing and other areas.It is widely used.The Erligou Station of Beijing Metro Line 16 studied in this paper is located at the intersection of Sanlihe Road and Chegongzhuang Street.The traffic around Erligou Station is heavy and the pipelines are complicated.The excavation section area is large(super large section),the main structure of the station is shallowly buried(the buried depth is 8.9m),and the ground settlement needs to be strictly controlled.Compared with other construction methods,the PBA method has its unique advantages.This paper uses the Erligou Station of Line 16 as the engineering background to study the surface settlement,horizontal displacement of the surface and settlement changes of adjacent pipelines during the construction of the two-story,three-column,four-span station during the PBA construction process,and use Midas GTS NX finite element analysis software to establish Three-dimensional simulation model and calculation.The research content is as follows:1.According to the engineering geological characteristics of Erligou Station,using Midas GTS NX finite element analysis software,combined with the construction characteristics of the PBA method,the entire construction process is analyzed and simulated,and the actual measurement data of the construction site is analyzed and compared.2.Analyze the laws of surface settlement and horizontal displacement under different excavation stages(small pilot tunnel excavation,pile system construction,buckle arch construction,and main structure construction)under specific station structure conditions(two floors and four spans).3.The settlement of adjacent pipelines in each construction stage is studied and analyzed,and the actual measured value and the simulated value are compared.4.Study the influence of the different pilot tunnel excavation sequence on the ground settlement and horizontal displacement according to the actual engineering pilot tunnel excavation sequence(first center then second)and the previous experience of "first side first,then center".5.Study the law of surface settlement under different spacing between steel pipe columns.6.Analyze the important and difficult points of the Midas GTS NX finite element analysis software to establish the PBA construction method model,and provide corresponding solutions to provide richer modeling experience,provide reference for actual engineering,and provide convenience for future generations.