| Shield tunneling method is a widely used method in the construction of urban subway.Shield construction will cause the deformation of tunnel surrounding stratum and ground subsidence and then lead to surface subsidence,pipeline fracture,wall cracks and other disasters.So it is necessary to carry out the investigation of the deformation law of formation in the process of subway construction.In this paper,theoretical analysis and numerical simulation of shield tunneling is carried out base on Shangxinlu station~Beikezhan station section of Xi’an metro Line 4.The main content and conclusions are as follows:In the process of shield tunneling,the deformation near the middle part of railway box culvert right above the tunnel is maximum.The maximum deformation of the railway is4.54 mm,which is close to the measured value.Passenger dedicated railway line will be safe according to the established control standards.The 3D numerical simulation shows that single shield tunnel construction causes settlement trough.Two shield tunnel constructions cause a superposition of two settlement troughs.The final settlement of the ground is less then 6mm.A complete numerical model includes the consideration of engineering geological conditions,relative construction parameters,non-linear properties of soils,strength reduction of shield segments,the influence of grouting layer and other factors.The numerical results are close to the measured value.Combined with other auxiliary measures the shield construction has a relative small impact on the structure of passenger dedicated railway line.The safety of railway operations is ensured. |
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