Abstract: To study the environmental vibrations induced by train loads, an analytical model for a track coupled with a layered transversely isotropic (TI) ground is developed. The model can consider the alternate distribution of TI elastic and poroelastic layers in the ground to describe soils and rocks under different moisture conditions compared with existing models comprising only one type of medium. Based on the analytical model, the governing equations of TI media are solved firstly using Fourier transform and a potential function method. Then the exact stiffness matrix method is adapted to derive solutions to the layered ground with different media. Finally, the dynamic response of the coupled system is obtained by using the governing equations of the track and inverse integral transformation. The influences of groundwater existence and transverse isotropy on the vibration of track and ground are investigated. It is found that the influence of the groundwater existence in the TI poroelastic layer on the track force amplification factor is significant at load frequency lower than 200 Hz. The ground surface vibration attenuates faster with the distance from the track center for a larger ratio of the horizontal elastic modulus to the vertical one. The maximum vertical stress magnitude occurs within 1 m from the ground surface. The critical speed of the displacement and stress increases with the increasing ratio of the horizontal elastic modulus to the vertical one.

Key words: track, transversely isotropic, analytical model, alternate distribution, exact stiffness matrix, dynamic response