Static and dynamic response of bedding structure in railway tunnel

On the basis of quasi-static loading, we selected the bedding structure of a railway tunnel under the rail as a research model and implemented static and dynamic analysis through numerical simulations. About bedding structure, we meant the concrete base between the ballast and the soil foundation under the rail structure of a tunnel. Four models of the tunnel bedding structure were analyzed under the static and impact loads of the train by simulating the infrastructure under the track. In this study, we examined the relationship between the vertical dynamic coefficient and the train velocity, and also analyzed the damage sustained by the bedding structure under the static and dynamic loads. It is suggested that the damage in the concrete bedding is detected in the longitudinal direction, immediately below the two rails, and that this damage is likely to occur not from attaining an elastic limit under static loads but more likely from damage accumulation in fatigue due to repeated loadings. In the bedding structure constructed with a steel bar, the attenuation rate at which the stress is transferred from the top bedding to the upper surface of the foundation rock will be high.