Theoritical Analysis And Numerical Simulation On The Interaction Between Continuously Welded Track And Tunnel Floor Due To Traversing Excavation

With the large-scale construction of urban subway,it will be bound to appear that more and more newly-built subway lines traverse the existing subway tunnels.Traversing construction induces deformation of the existing tunnel and track structure.Deformation difference or even detachment will arise among rail,track bed and tunnel floor since track and tunnel floor are separated structures.The deformation of track structure affects the comfort and safety of the existing metro,and relates to construction methods of new tunnel and safeguard measures of track structure.It is important to determine the deformation of the existing track structure accurately as the deformation of the tunnel floor is known.However,the present mechanical analysis of track structure in the traversing construction neglects the interaction between track and tunnel structure.The deformation of track and tunnel floor is always regarded as the same.Deformation and internal forces of track structure induced by deformation of tunnel structure mainly rely on numerical simulation,with few researches on analytic calculation methods.Therefore,it is of important theoretical and practical significance to study the interaction between track and tunnel structure.In this paper,interaction between track and tunnel structure,as well as methods to calculate the deformation and internal forces in track structure were studied by theoretical analysis and numerical simulation.The main results are as follows:(1)A governing differential equation of track structure considering large deformation was established.A step function H(x)was introduced in the differential equation to consider the detachment between track and tunnel structure.Fourier series method was used to solve the governing differential equation.The validity of the Fourier series solution was verified by numerical simulation.(2)Finite element models taking into account the interaction among rail,elastic support slab(steel spring floating slab)and tunnel floor were established by using FEM software ANSYS.A kind of compression-only link unit was used to simulate the possible detachment among rail,track bed and tunnel floor.(3)Taken into consideration were influence factors as follows:the deformation types of tunnel floor,the maximum deformation of the tunnel floor,the width of settlement trough,and the deformation joints in between track beds.Deformation and internal forces of track structure,detachment among rail,track bed and tunnel floor were calculated by theoretical method and numerical simulation respectively.Laws of interaction between track and tunnel structure were discussed.(4)A case study was carried out.The theoretical solution and the numerical solution are consistent.By comparing the calculated values with the measured values,it can be concluded that both the theoretical and numerical methods proposed in this paper can effectively predict the deformation and internal forces of track structure.