Effects of track irregularities on environmental vibration caused by underground railway

• A train-track-tunnel-soil interaction model close to practical situation is developed.
• 3D and 2D tunnel-soil models are respectively used in middle and two-sides tunnel.
• Effects of four types of track irregularities on environmental vibration are studied.
• Environmental vibration induced by short wavelength track irregularity is significant.
• Vibration acceleration and frequency distribution of ground surface are obtained.

A mixed two- and three-dimensional model is developed to simulate the dynamic track-tunnel-soil interaction in underground railway with ballastless track taking into account the moving train comprising a number of carriages, the track irregularities, and interaction among various components of the system. The effects of different track irregularities on the environmental vibration generated by underground railway with direct fixation and floating slab tracks are investigated. The results show that random track irregularities have large effects on the environmental vibration compared with perfectly smooth track condition. For direct fixation tracks, the environmental vibration induced by the irregularity of short wavelength is more significant than that induced by the irregularity of medium wavelength. However, for floating slab tracks, the environmental vibration induced by the irregularity of short wavelength is less significant than that induced by the irregularity of medium wavelength. The track irregularity samples measured by track geometry measuring car should therefore be used together with the short-wavelength random track irregularity for accurate prediction of the environmental vibration induced by underground railway with direct fixation track.