2015 Volume 56 Issue 1 Pages 26-32
This paper describes research into the dynamic responses measured on a commercial-line with ballasted track using sensing sleepers and sensing stones both of which were developed by the author, for the purpose of gaining new knowledge that will contribute to measures against track deterioration and effective track maintenance. The research further analyzed the measurement results in terms of the spectral characteristics of ballast behavior and the vertical natural vibration characteristics of ballast layers. The results of the spectral analysis show that the rigid-body vibration mode of sleepers is in a frequency range lower than 100 Hz and also reveal that the elastic vibration modes of ballast layers are in a frequency range as wide as 400 - 800 Hz. This series of analyses suggests the possibility that the dynamic load of a passing train is hard to damp, affected by its resonance. Furthermore, the author performed a full-scale drop-weight impact test and found from the test result that when the impact load works on a ballast layer, unloading causes abrupt release of stress, which led to decreased contact force between particles and a jumping behavior in the ballast layer.
