Near-field vibrations in railway track on soft subgrades for semi high-speed trains

For the development of a high-speed rail network in urbanised areas, ground vibration and associated damage to surrounding structures are major concerns. The problem becomes critical especially in areas with soft soil deposits due to amplification of vibration during Rayleigh wave propagation. In the present study, near field ground vibrations from a high-speed rail ballasted track are predicted for an area which contains predominantly soft marine clay deposits. A two-dimensional finite element model coupled with infinite boundaries is developed in ABAQUS. Using the finite element model, the vibration in terms of peak particle velocity (PPV) and root mean square (RMS) velocity is determined for different train speeds and soil profiles, at varying distances from the track centre. Different soil profiles are considered in this study by varying the thickness and depth of the soft clay layer. From the results, it was observed that maximum ground vibration happens when the train speed is close to the Rayleigh velocity of the soft clay layer. Further, the safe limits for residential and sensitive structures are determined for different conditions based on peak particle velocity. Considering human discomfort during vibration propagation, the vibration level in decibel scale is determined for different track configurations.