Three-Dimensional Numerical Modeling of Train-Induced Vibration with Special References to Track Irregularities and Soil Stiffness

In this study, a three-dimensional numerical model was developed to simulate the complex dynamic phenomenon of railway tracks and to predict the free-field ground vibrations. The dynamic forces of the wheel-rail were expressed as a function of the wavelength and the amplitude of track irregularity, and a user-developed subroutine was also developed to discretize the moving load according to train speed and the length of the traveled element. Then, a 3D finite differences model was validated using in situ measurements. The validated numerical model was extended to study the effect of train speed, rail irregularities, and soil stiffness on vibration levels. The results revealed that faster trains produce larger vibrations that exceed the human threshold even at a distance of 15 m from a railway track of good quality. The poor track generated severe ground vibrations above the human and structural thresholds at significant distances from railway tracks. Moreover, it was found that increasing soil stiffness by ten times leads to a noticeable decrease in the vibration amplitude by about 40%. The developed 3D numerical model provides a valuable tool for preventing the undesired impacts of vibrations on the nearby environment.