Taking the construction of the cross section between the existing Pingfengshan tunnel and the new Pinggongshan tunnel as an object,the impact of the upper span construction on the deformation and structural force of the existing tunnel was analyzed by using numerical simulation method.The results show that the construction of the new tunnel has less impact on the displacement,deformation of track surface settlement and rail height difference of the existing tunnel,which is in line with the relevant specification requirements;at the same time,the construction of the new tunnel leads to a reduction in the axial force of the secondary lining of the existing tunnel and an increase in the structural bending moment,but the minimum safety coefficient of 5.81,which is higher than the minimum value of 3.6 required by the specification,and it does not affect the safety of the operation of the existing tunnel.The research results have important guiding significance for the construction of overpasses on existing lines.
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