Analysis And Research On The Influence Of New Road Underpass Construction On The Operation Of Existing Railway Lines

With the modernization of railway and the continuous improvement of high-speed railway network,the speed of trains has been greatly improved,the frequency and operation density of trains have also been continuously increased,and the safety requirements for adjacent construction projects have become increasingly stringent.At the same time,due to the accelerating pace of urbanize construction and the gradual rise of modern infrastructure,the intersection of roads which is new or renovated and municipal projects and existing railways tends to he dense,and the ineteraction between them becomes more common and complex.In this paper,based on the engineering examples of new roads under existing subgrade of railway and passenger dedicated line,the influence of frame bridge underpass construction on existing railway bed and 'U-groove' construction on high-speed railway bridge is deeply analyzed by finite dement simulation method.The main research contents are as follows:(1)Relying on 'Shen-Jia-Hu' motorway,which uses underpass frame bridge construction under existing railway bed of 'Xuan-Hang' Railway.Based on the finite element simulation of excavation of foundation pit near the railway bed in soli soil area,the in fluence of foundation pit construction process near the railway is analyzed,and a reasonable supporting scheme is proposed.Numerical analysis is carried out on the influilence of different speed limited conditions on railway lines,combining railway operating conditions,the organization of construction,risk management and other factors,The speed limit during construction is recommended to 45km.Research on the inlluence of the length of constructing step for frame bridge underpass in soft soil area.This paper analyzed the displacement influence of four constructing step lengths of 0.5m,1.0m,1.5m and 2.0m under the conditions of diferent speed limit of the train,and proposes the construction scheme of Step and Fast-Pushing'.(2)Aiming at the example of 'U-grooving' structure of Shen-Jia-Hu motorway underpassing the Existing 'Ning-Hang' passenger dedicated line,The influence of'U-groove' foundation pit construction under existing bridge structure is analyzed by means of modified foundation reaction method and finite element method.The comparison with the measured results verifies the effectiveness of the support scheme.