Analysis Of The Influence Of Shield Construction On Adjacent Pressure Pipelines In Clay Stratum

With the progress and development of society,the population of cities has generally increased.Consequently,the available space on the ground is increasingly scarce with the construction of large-scale buildings,entertainment facilities and so on,which inevitably leads to traffic congestion.Practice shows that the establishment of Metro can effectively decrease traffic congestion.t Currently,China’s rail transit has developed rapidly.Shield tunneling is the main construction method of urban rail transit construction.Shield tunneling will inevitably cause surrounding rock disturbance and ground deformation,which will lead to the distortion of adjacent pipelines,For example,distortion of nitrogen and oxygen pipelines,will cause major safety accidents.In this paper,the author used analysis methods,numerical simulation and in-situ monitoring,and took Hefei Metro Line 3 as reference,a three-dimensional analysis model of tunnel-soil-pipeline which is established by using MADAS software.The main conclusions are as follows:(1)Based on the engineering characteristics of expansive soil layer,the influence of expansive soil layer on shield driving is analyzed.(2)Based on the overlay Peck’s formula,the observed values are slightly larger than the theoretical values by comparing the theoretical values with the monitored values,but the settlement laws of the two are basically the same.(3)Using Midas finite element software to simulate the shield tunneling direction parallel to and vertical to the pipeline,and analyze the influence of pipeline parameters(pipe material,diameter,depth)and horizontal spacing of the tunnel on the pipeline settlement.The results show that the parameters of the pipeline itself have less influence on the pipeline settlement,while the horizontal spacing of the pipeline and tunnel has greater influence on the pipeline settlement,with the diameter,tube,tube spacing.Depth of buried pipeline and other factors do not change significantly,while the horizontal spacing between tunnels and pipes increases significantly.(4)Using Midas finite element software to simulate the two working conditions of shield tunneling direction parallel to and perpendicular to the pipeline,and analyze the influence of tunnel construction parameters(depth,diameter,distance between two tunnel centerlines)on pipeline settlement.The results show that tunnel construction parameters have a greater influence on pipeline settlement,with the increase of tunnel diameter,the depth of tunnel buried from deep to shallow,and the distance between two tunnel centerlines.From large to small,the subsidence of the pipeline is increasing.