Damage detection of ballastless railway tracks by the impact-echo method

The objectives of this study were to investigate the impact response of ballastless railway tracks and to study the feasibility of using the impact-echo method for the detection of typical damage to ballastless tracks. Numerical studies were carried out to acquire the transient responses of ballastless tracks subjected to impact. The numerical results were verified by experimental studies on ballastless tracks with and without damage. It was found that there is a predominant frequency whose value depends on the dimensions of the ballastless track for a given P-wave speed in concrete. The presence of damage was found to disrupt the modes of vibration. A shift of the predominant frequency to a lower value was found to be a key indication of the presence of damage. Multiple wave reflections between the impact surface and the damage surface produced a large-amplitude peak in the spectrum at a frequency corresponding to the depth of the damage.