Analysis Of Effects Of Urban Metro Tunnel Excavation On Existing Pipelines

With the continuous development of urban economy, urban subway play an increasingly important role, it brings to the city of great economic benefits, social benefits and military benefits, but also has brings a series of safety problems to complex municipal pipe network. When the subway construction crosses underground pipelines, tunnel excavation will inevitably lead to the disturbance of the underground pipeline,making it stress and deformation. If pipeline deformation is too large, more than the allowed safety deformation, pipeline will crack, even fracture, leading to accidents. As the lifeline of the city, its security or not directly endanger the normal national production and construction and people’s life and property security, so the research on pipeline deformation law has important realistic meaning and profound theoretical significance. This paper calculate the deformation and internal force of pipeline in a typical winkler Beam on elastic foundation model,and systematically studys deformation law of underground pipeline combined with field measurement and numerical simulation. The main contents and conclusions of this study are as follows:(1)Summarize the relevant knowledge of underground pipelines, including pipelines categories、 materials、 interface method and monitoring method, etc.(2)Differential control equation of pipeline is established based on the Winkler Beam on elastic foundation model, Then solve the differential equation and obtain displacement and internal force expression of the pipeline, finally carrys on the parameter sensitivity analysis and works out the laws of effects of different factors on pipeline,including the buried depth 、 material、 angle of the tunnel and pipeline 、 diameter and wall thickness, etc.(3)On the background of Xi ’an metro line 3 Jiangong road- Xianning road interval,studying the influence law of subway tunnel excavation on vertical and parallel pipeline, the conclusion points out that in the shallow depth excavation method, when the pipeline verticals to the tunnel towards,pipeline deformation curve is in the form of "twin peaks", the maximum subsidence respectively locating above the tunnel axis,and when the pipeline parallels to the tunnel towards, pipeline deformation will occur differential settlement due to different sequence of tunnel construction, but the final settlement tends to be consistent.(4)Comparative analysising the influence of different construction methods on pipeline by numerical simulation,the conclusion points out that the degree of the biggest influence on the pipeline is bench method in the four construction methods,followed by the reservation core of annular excavation method and CRD method,the minimal influence is the double side heading method.(5)The safety discriminant method are proposed, and puts forward the safety control measures of underground pipeline.