Experimental study of the frequency-domain characteristics of ground vibrations caused by a high-speed train running on non-ballasted track

An in-situ test to obtain vertical, transversal and longitudinal ground velocities and accelerations caused by high-speed trains was performed alongside the Chinese high-speed railway line between Beijing and Shanghai. The test results indicate that due to excellent track quaity and consolidated infrastructure, whether if the train speed is below or above the Rayleigh wave speed, the dominant frequencies of both the vertical ground velocity and acceleration are both integral multiples of the trainload frequency generated by the centre distance of two neigbouring cars. The frequency-domain distribution of the ground velocity is more sensitive to soil stiffness than is the ground acceleration; this is especially the case for the first dominant frequency. Whether the frequency amplitudes of the vertical ground vibration are higher than the horizontal vibrations depends on the soil stiffness. The greater the soil stiffness, the higher is the frequency-range of the vertical ground vibration compared with that for the horizontal vibration, and the smaller is the difference between the three-dimensional frequency-weighted ground vibration level and the vertical vibration. Thus, effects of horizontal ground vibrations cannot be ignored when the foundation soil is soft.