Research On Deformation Law Of Upper Pipeline Caused By Rectangular Pipe Jacking Construction

In recent years,with the construction of urbanization,the urban population has grown rapidly and the problem of traffic has become increasingly serious.Due to the limitation of urban land resources,large-scale surface excavation will have a great impact on urban traffic conditions and urban environment,so it is an inevitable trend to prohibit large-scale surface excavation in cities.The development of underground space will receive more and more attention.As a non-excavation method,the pipe jacking method will be more and more applied in urban construction.In this paper,basing on the No.8 entrance and exit of a station of Zhengzhou Metro Line 3,the influence of the large-section rectangular pipe jacking construction on the deformation of the large-diameter pipeline above is studied,and the law of pipeline displacement and stress under different factors is obtained,and the influence of a single factor on pipeline displacement is analyzed.This paper designs the reinforcement scheme of pipeline and provides certain technical guidance for the following urban construction in Zhengzhou area.The main research contents of this paper are as follows:(1)This paper analyzes the relevant data of the influence of the rectangular pipe jacking construction on the pipeline,studies the disturbance mechanism of the pipe jacking construction on the stratum and the pipeline,and gives the calculation formulas of the pipeline displacement,bending moment and shear force.These studies provide theoretical research for subsequent analysis.(2)This paper uses ABAQUS finite element software to build a three-dimensional model and analyzes the law of pipeline displacement,bending moment,and shear force in the case where the position of the jacking pipe and the tunnel is vertical and parallel.This paper also studies the influence of support pressure of working face,grouting pressure,pipeline diameter,pipeline thickness,and pipeline depth,and gives recommended values for support pressure and grouting pressure.(3)With the help of the grey incidence theory,this paper takes the maximum vertical displacement of the pipeline as the reference sequence and different influencing factors as the comparison sequence to study the sensitivity of a single factor.The correlation degree of each influencing factor to the pipeline displacement is calculated when the positions of the tunnel and the pipeline are vertical and parallel.This paper also judges the influence degree of each factor:(1)In the case where the location of the tunnel and pipeline is vertical,the degree of influence on vertical pipeline displacement from large to small is pipeline diameter,support pressure,grouting pressure,pipeline depth,pipeline thickness;(2)In the case where the position of the tunnel and pipeline are parallel,the degree of influence from large to small is the support pressure,grouting pressure,pipeline diameter,pipeline depth,and pipeline thickness.(4)In the case where the location of the tunnel and pipeline is vertical,the MJS method is used to reinforce the pipeline.Compared with the situation before reinforcement,the maximum vertical displacement of the pipeline is reduced by38.13%,and the maximum lateral displacement is reduced by 73.33%.and the maximum longitudinal displacement is reduced by 41.03%,and the maximum positive bending moment and maximum negative bending moment of the pipeline are reduced by 52.99% and 78.58% respectively,and the maximum positive and negative shear forces are both reduced by 48.02%.The effects of grouting replacement rate,reinforcement width and reinforcement depth on pipeline deformation are analyzed.The proposed values of replacement rate,reinforcement width and reinforcement depth are given.After the scheme is used in engineering practice,the monitoring data is not much different from the numerical calculation results,which proves the rationality of the reinforcement scheme.