Focusing of Rayleigh waves generated by high-speed trains under the condition of ground vibration boom

TL;DR

This paper theoretically investigates how Rayleigh waves generated by high-speed trains can become focused due to track bends or acceleration, leading to increased ground vibrations along specific lines, similar to sonic booms.

Contribution

It introduces a theoretical analysis of Rayleigh wave focusing caused by train movement and track geometry, highlighting potential vibration amplification effects.

Findings

Focusing of Rayleigh waves occurs near track bends and high speeds.

Energy concentration along caustic lines increases ground vibration amplitudes.

Numerical calculations illustrate the focusing effects under different train conditions.

Abstract

In the present paper, the effects of focusing of Rayleigh waves generated by high speed trains in the supporting ground under the condition of ground vibration boom are considered theoretically. These effects are similar to the effects of focusing of sound waves radiated by aircraft under the condition of sonic boom. In particular, if a railway track has a bend to provide the possibility of changing direction of train movement, the Rayleigh surface waves generated by high-speed trains under the condition of ground vibration boom may become focused. This results in concentration of their energy along a simple caustic line at one side of the track and in the corresponding increase in ground vibration amplitudes. The effect of focusing of Rayleigh waves may occur also if a train moves along a straight line with acceleration and its current speed is higher than Rayleigh wave velocity in the ground. The obtained results are illustrated by numerical calculations.