Sensitive Parameter Analysis Of Pressure Pipeline In Shield Construction

With the gradual acceleration of urban development and the rapid development of social economy,the use of subway can well solve the problems of insufficient urban ground space and traffic congestion.In the process of subway tunnel construction,it is inevitable to encounter unavoidable municipal pipelines and other structures.It is particularly important to ensure the safety of municipal pipelines in construction,otherwise it will cause immeasurable losses.In this paper,based on the engineering background of long-distance accompany behavior of oxygen pipe in in-out line interval of Tianshui Road Parking Yard of Hefei Rail Transit Line 1 Phase III Project,the influence of shield tunnel excavation on the settlement of pressure pipeline is simulated by FLAC 3D software.Combined with the in-situ monitoring data,the applicability and feasibility of the model are verified.The influence of different parameters on the settlement of pressure pipeline is analyzed by controlling the change of single variable.Finally,the influence of sensitive parameters on the settlement of pressure pipeline is analyzed by using the grey correlation theory.The following conclusions are drawn :（1）Pipeline settlement decreases with the increase of pipe-soil relative stiffness ratio,but the influence of pipeline material on pipeline settlement is limited.When the pipe-soil relative stiffness reaches 0.15,the change of pipeline settlement is small with the increase of pipe-soil relative stiffness ratio;for different pipeline internal pressure,the trend of pipeline settlement is similar,with the increase of internal pressure,the pipeline settlement decreases gradually;（2）With the increase of vertical spacing of pipeline tunnels,the overall change trend of pipeline settlement is similar,but the pipeline settlement decreases gradually.With the increase of vertical-diameter ratio,the settlement value of pipeline decreases gradually;with the increase of the transverse spacing of the pipeline tunnel,the overall trend of the pipeline settlement is similar,but the pipeline settlement decreases gradually.With the increase of the aspect ratio,the settlement value of the pipeline decreases gradually;with the increase of the angle between the pipeline tunnel,the settlement curve of the surface and pipeline at the axial position of the pipeline transits gradually from the approximate linear settlement curve to the peck settlement curve.The smaller the angle between the pipeline tunnel is,the greater the influence of shield tunnel excavation on the pipeline is,and the larger the settlement value of the pipeline is.The width of the surface settlement curve at the axial position of the pipeline is 1/sinθ times of the width of the settlement curve at the angle of 90°.（3）Different earth pressure,pipeline settlement trend is the same,with the increase of earth pressure,pipeline settlement decreases gradually;for different grouting pressure,the trend of pipeline settlement is the same,with the increase of grouting pressure,the pipeline settlement decreases gradually;（4）The grey correlation of the maximum value of the settlement of the existing pipeline in descending order is: vertical spacing of the pipe and tunnel,horizontal spacing of the pipe and tunnel,angle between the pipe and tunnel,grouting pressure,soil bin pressure,pipeline material and internal pressure of the pipeline.Influence of vertical distance between pipe and tunnel on settlement of existing pressure pipeline is largest.;the lateral spacing of the pipes and tunnels and the angle of the pipes and tunnels also have a greater influence on the settlement of existing pressure lines;the grouting pressure,the pressure of the soil silo,the material of the pipes and the internal pressure of the pipes have a smaller influence on the settlement of the pressure lines.Figure [54] table [6] reference [71]...