Excessive ground vibrations associated with trains travelling at trans-rayleigh speeds

A very large increase in ground vibrations generated by high-speed trains (ground vibration boom) has been predicted theoretically in 1994 by the present author. The first experimental observation of this phenomenon was reported in 1997 by C. Madshus who worked with his team on the assessment of the newly opened high-speed railway line from Gothenburg to Malmo in Sweden. As the ground on the site of observation was very soft, the ground vibration boom could be observed for train speeds as low as 160 km/h. It is now well understood that excessive vibrations associated with ground vibration boom represent a serious hazard for the built environment, especially in the cases where high-speed lines are built on very soft soil. The present paper reviews the current status of the theory of ground vibration boom from high-speed trains. Among the problems to be discussed are contributions of different generation mechanisms, effect of track wave resonances on generated ground vibrations, effects of layered geological structure of the ground, waveguide effects of the embankments, and focusing of generated waves due to the track curvature. The results of theoretical calculations are compared with the existing experimental observations.