Research on structural deformation law and allowable deformation of shield tunnel underneath passing high-speed railway tunnel

Abstract

Our country's urbanization is developing rapidly. In order to reduce the occupation of space, the construction of high-speed railway more in the form of tunnels. At the same time, the construction of subway is booming, and many high-speed railways and subways cross each other. In order to study the structural deformation law of the shield tunnel under the highspeed railway tunnel, taking a shield tunnelling project of a railway line under a high-speed railway tunnel as an example, the influence of the construction of new shield under an existing high-speed railway tunnel on the settlement deformation and stress change of existing structure is analyzed through ANSYS. This paper focuses on the deformation of each structure in each excavation process and the deformation coordination relationship between rail, foundation under rail and highspeed railway tunnel, and explores the allowable deformation of tunnel structure from the perspective of tunnel structure crack control requirements. The results show that: 1) With the progress of shield construction, the deformation of track structure and civil structure is increasing, and the deformation law is generally the same: tunnel structure settlement displacement < supporting layer settlement displacement < track slab settlement displacement < rail settlement displacement. 2) The settlement of the supporting layer in the track structure and the change of the track height basically show a linear relationship: when the settlement deformation of the foundation support layer under the track increases, the settlement of the rail increases, the track irregularity intensifies, and the track height irregularity increases. 3) From the perspective of crack control of tunnel structure, the allowable deformation value of high-speed railway tunnel structure is 20mm.