The Study On Deformation And Internal Force Of Pipeline Caused By City Tunnel Construction Passing Underneath

In recent years,China’s urbanization process is accelerating,and populations continue to gather in cities.Urban transport issues are becoming more and more important.To alleviate traffic congestion,it’s an important measure to develop rail transit and underground railway.Urban subway lines are complicated.Crossing project is a common and important project.Various municipal pipelines which maintaining the normal operation of the city are the blood vessels of the city.The safety problem of the subway tunnel crossing the pipeline can’t be ignored.In this paper,the effects of deformation and stress on the pipeline during the vertical cross of the pipeline are studied with theoretical research,numerical simulation,and engineering measurement methods.Pipeline deformation and stress are closer to the actual situation of the project by taking horizontal displacement,axial force of pipeline and pipe-soil friction into account.,which is especially suitable for large deformation of pipelines.The specific research results are as follows:(1)Based on large deformation theory,the differential equations of pipeline considering the axial displacement,axial force and pipe-soil friction are derived.The finite difference method is used to solve the problem,and the calculation method of pipeline deformation and internal force is obtained.(2)Based on the numerical simulation method,the variation law of pipeline deformation and axial stress during the vertical penetration of the tunnel is studied,which confirms the correctness of the theoretical derivation results.Based on the grey relational theory,the sensitivity analysis of the influence of the pipeline tunnel depth,the elastic modulus of the pipe soil and the friction coefficient on the deformation and internal force of the pipeline is studied,and the ranking of the influence degree is obtained.(3)Based on the engineering case of Tsinghuayuan Tunnel under Chengfu Road,through analysis of monitoring data of pipelines and surface and fitting of subsidence curve,and comparing with theoretical calculation results,the two results are relatively close.The theory of this paper is also applicable when the pipeline deformation is small,and the theoretical prediction can be used as a reference for practical engineering guidance.(4)This paper summarizes the domestic and foreign pipeline risk assessment standards and protection and reinforcement measures,analyzes the main steps of pipeline risk assessment,and proposes a reference scheme that uses pipeline strain and surface settlement as pipeline risk control indicators.Based on the allowable strain limit of the pipeline,the upper limit of the applicable range of the pipeline’s small deformation theory and the surface settlement limit of the large deformation theory are recommended for engineering construction reference.