Abstract：The dynamic response of the system composed of rail wheel，rail and tunnel under railway is analyzed with elastoplastic finite element method. The influence of the structure under rail with bigger stiffness on variation regularity of vertical dynamic stress in roadbed is studied. The additional dynamic stresses of tunnels with different depths are also discussed. The ideal touch model between tie and bed and the ideal elastoplastic dynamic model of soil are adopted for analysis. The analysis results indicate that the attenuation of additional dynamic stress along depth is reduced with existence of the structure under rail. The deeper the tunnel is，the lower the whole level of dynamic stresses in roadbed is and the smaller the influence on tunnel is. In addition，the fatigue failure of concrete due to long-term train-induced dynamic load should be considered in design.
