The effect of the frequency-dependent stiffness of rail pad on the environment vibrations induced by subway train running in tunnel

The influence of the frequency-dependent stiffness of rail pad on the frequency distribution of vibrations created by a subway train running in tunnel is investigated using a frequency-domain algorithm. The theoretical approach combines vehicle-track coupling dynamics and spectrum analysis using the finite element method. The proposed approach is validated by a comparison with measured data. The comparison further shows that the theoretical approach and the selection of calculation parameters are reasonable and they create high calculation accuracies in the considered frequency range. Compared with a constant stiffness pad, the frequency-dependent stiffness of rail pad has little effect on vibrations below the one-third octave center frequency of 25Hz; however, it significantly changes the vibrations observed above that center frequency. It is also found that simply increasing the constant stiffness of rail pad can lead to predictions of the vibration that have only a small error in either the low-frequency or high-frequency domains.