Analysis Of Deformation Characteristics Of The New-built Subway Tunnel Passing Under The Different Structuring Forms Existing Subways

With the rapid growth of urban population,the demand for rapid,punctual and large of public transportation is increasing.The development of urban underground rail traffic is getting faster and faster,and the railway line network is more and more dense.Therefore,the subway tunnel under the subway construction is inevitable.If the design and construction is not appropriate,the tunnel above the existing structure will produce greater deformation.Even affect the operation and structural safety of existing lines and cause catastrophic accidents.The deformation law of different types of existing subway lines is analyzed by means of data statistics,refine numerical,simulation and field monitoring.And the existing line Chaoyangmen station project example is used for verification,the main work and achievements are as follows:(1)For 22 Beijing subways crossing the existing line project case,18 sets of data were collected at the same time.For the integral structures with movement joints,the discontinuous deformation of the existing structures occurs at the movement joints,and the existing structures exhibit rigid characteristics;For the integral existing structures without movement joints,the existing structures exhibit flexible characteristics;for the shield assembly structure,the deformation of existing structures is flexible.It shows that the presence of movement joints has a significant effect on the deformation behavior of existing tunnel.(2)According to the statistical results,the pipe deformation between movement joints is the whole settlement,rigid rotation and flexural deformation.In the same project,the pipe deformation characteristics of different pipe sections are different,and different crossing conditions are different characteristics deformation of pipe.(3)Through numerical simulation calculation,a variety of different crossing conditions are given based on the relative position of the existing tunnel movement joints and the new tunnel,and the overall deformation of the existing line and the deformation behavior of each pipe are analyzed.Under the same construction conditions,the relative positions of the existing tunnel movement joints and the new tunnel are different,and the existing tunnel deformation behavior are different.When the axis of the new tunnel is located directly below the deformation joint,the settlement of the existing tunnel is large,the deformation range is small,and the pipe section is rigid rotation.When the axis of the tunnel is located directly below the pipe section,flexure of pipe between with movement joints and differential settlement of pipe at the movement joints is large(4)Three-dimensional discontinuous contact model of soil-liner-bolt was established.Based on the discontinuity between the segment and the soil and segment joints,the deformation characteristics of the existing shielded tunnel were calculated and analyzed.The existing shield was assembled.The deformation of the tunnel presents a flexible feature.The open angle between the shield segments is small,and the deformation is mainly caused by the sinking of the segment.(5)Based on the three factors of different soil parameters,existing tunnel depth,and existing tunnel stiffness,the deformation behavior of existing structures with different factors are analyzed:1 As the soil parameters increase,the deformation of the existing tunnel and the deformation of the pipe decrease in inverse proportion decreases,2 As the existing tunnel depth increases,the deformation of the existing tunnel and pipe deformation increase in a linear proportion;3 For the integral tunnel with movement joint,with the increase of the existing structure stiffness with reduced structural settlement and increased deformation range,the whole settlement of pipe between movement joints and differential settlement changes little,but the flexure decreases with increasing stiffness.(6)Through calculation and analysis,in the construction of the new subway below the existing railway line,the deformation of the integral tunnel with movement joints exhibit rigid behavior,the deformation of the integral tunnel without movement joints and the shield tunnel exhibit flexible behavior.At the same time,through the actual engineering case.A comparative analysis was carried out to clarify the relationship between numerical calculations and filed measurements.This study was validated.