Study On The Safety And The Protection Of Changzhou Metro Line 1 Underpass Shanghai-Nanjin Railway And Shanghai-Nanjin Intercity Railway

With the rapid development of urban rail transit and the wide application of shield method in subway tunnel construction,a large number of shield tunnels have been constructed under the existing railways.The construction of shield tunnel has changed the original stress field of the railway foundation,causing disturbance to the soil layer and the displacement of the soil layer,which will inevitably lead to the deformation of the railway track and affect the operation of the railway.Especially for the ballastless track of intercity high-speed rail,once the roadbed of ballastless track is settled,it will inevitably affect the smoothness of the track and even cause the concrete to break.These deformations will cause incalculable serious consequences to the railway operation.Therefore,the safety analysis and strengthening measures of the existing railway subgrade are particularly important when the shield tunnel is worn under the railway line.The area from Changzhou Railway Station to Bo Ai station in Changzhou Metro Line 1 lies beneath the Shanghai-Nanjing intercity railway and Beijing-Shanghai general speed railway at Changzhou Railway Station,so the railway engineering is bound to put forward higher requirements on the construction work in shield interval.In view of the fact that there is no uniform standard for strengthening the shield tunnel under existing railway projects and railway safety evaluation,it is urgent to put forward a scientific reinforcement scheme and safety evaluation system for the soil layer.In this paper,the shield tunnel of Changzhou Metro Line 1 under railway engineering project is taken as the research object,based on detailed analysis of site engineering geological conditions by using finite element analysis software Plaxis2 D calculation of surface subsidence caused by changes in the construction of shield tunnel.The tunnel is above ground subsidence,subway line spacing less than 16 M,and the settlement trough is U respectively;Beijing-Shanghai general speed railway and Shanghai-Nanjing intercity line and the line safety control standards are analyzedto meet the requirements of the railway protection impact assessment;some effective methods and measures of safety protection are also put forward to make sure the relevant measures can reduce the impact on deformation of railway construction and to reduce the project risk finally.The Ansys software is used to calculate the force of the segment structure of the shield tunnel in the lower railway section,and the interval structure is checked and analyzed.According to safety analysis and impact on the existing protection caused by the shield construction of Changzhou Metro Line 1 tunnel under railway,engineers have put forward suitable safety analysis system for Changzhou area tunnel beneath the existing railway,which has a large amount of theoretical significance and practical value.