Ground vibrations from tracked vehicles: theory and applications

Over the last decade, much of attention was paid to the use of traffic-induced ground vibrations for the purposes of remote detection and monitoring of heavy military vehicles, such as tanks and armoured personnel carriers. A promising method of detection and identification is the one using the information extracted from ground vibration spectra generated by heavy military vehicles, often termed as their seismic signatures. The aim of the present work is to discuss the analytical approach to the prediction and interpretation of ground vibration spectra from heavy military vehicles. The analysis in this work is limited to tracked vehicles only. The modelling of track periodic irregularities (discontinuities) is considered from the point of view of their effect on the resulting dynamic forces applied from a vehicle to the ground and on the generated ground vibration spectra. Also, the effects of layered ground structure and of changes in wheel tyre compliance are considered for different values of ground and tyre parameters. It is shown that the obtained ground vibration spectra contain clearly identifiable peaks at frequencies associated with some characteristic vehicle parameters, such as track periodicity, distance between the nearest wheel axes, and vehicle speed. Although the relative amplitudes of these peaks vary with changes in layered structure, track irregularity profile, or tyre compliance, their positions on the frequency axis are robust and depend on track periodicity, distance between the nearest wheel axes, and vehicle speed only. A discussion follows on possible use of these spectral peaks for determination of these vehicle parameters and thus for vehicle identification.