| Today’s urban subway development is in a critical period.The construction of the subway is closely related to people’s lifestyles,and it also increasingly represents the prosperity of a city’s economic development.The impact of shield tunnel construction on the surrounding environment is an important research topic today.The disturbance problem of shield tunnel construction on adjacent underground pipelines is prominent,especially the positional relationship between the shield tunnel and underground pipelines perpendicularly crossing.The discussion on the influence of pipeline deformation will directly affect the construction of urban subways.This thesis combines the research topics of domestic and foreign scholars on the impact of tunnel construction on pipelines,and through understanding the possible damage forms of pipelines in the construction of shield tunnels and the safety judgment criteria of pipelines,with the construction background of taiyuan metro line 2 from zhongxinjie west station to jinyang street station.The FLAC3 D Lagrangian difference numerical simulation analysis method and gray correlation theory analysis method are used to analyze the deformation effect of the adjacent vertical pipeline caused by the shield construction,and the following main conclusions are drawn:(1)Obtain the engineering examples and actual monitoring data,the numerical analysis method is used to obtain the simulated value of the ground surface settlement during the tunnel construction process.By comparing the measured and simulated data,the rationality of the numerical model is verified.At the same time,the displacement and deformation of the formation and the pipeline in various directions are studied.The results show that the displacement of the pipeline and the formation are mainly subsidence.(2)Using numerical simulation to study the impact of six main influencing factors on pipeline settlement: With the increase in the thickness of the pipeline overburden,the tunnel excavation rate and the diameter of the tunnel,the overall settlement and maximum settlement of the pipeline gradually increase;With the increase of pipeline diameter,tunnel face support pressure ratio and tunnel distance,the overall settlement and maximum settlement of the pipelinegradually decrease;as the tunnel excavation rate and tunnel diameter increase,the main settlement area of the pipeline expands.The maximum settlement produced by the pipeline is approximately proportional to the thickness of the overburden,the supporting pressure ratio of the tunnel face,and the diameter of the tunnel.(3)Using gray correlation analysis method,the maximum settlement of pipelines is used as an indicator,the sensitivity of each influencing factor is compared and ranked,and the sensitivity to the influence of pipeline settlement is from weak to strong.Digging rate,supporting pressure ratio of tunnel face,thickness of pipeline overburden,pipeline diameter,pipe-tunnel spacing,tunnel diameter.(4)The maximum settlement of the pipeline during the tunnel construction is 30.284 mm.After the protective measures of the steel casing are added,the maximum settlement of the pipeline is reduced to 22.015 mm,and the settlement is reduced by about 27.32%.The numerical analysis results of the casing protection show that the protective measures have Certain effect. |
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