Analysis of the vibration alleviation of a new railway sub-ballast layer with waste tyre rubber

[EN] This paper focuses on the assessment of the vibration behaviour of granular sub-ballast materials mixed with rubber particles from scrap tyres. The main objective is to evaluate whether these mixes attenuate vibrations caused by passing trains, and if so, to what extent. Several laboratory and field tests were carried out to monitor the response of such materials to various excitation sources. The results show that under controlled laboratory conditions, the addition of rubber (up to 5% by weight) greatly increases the damping ratio and reduces vibration. Field tests also show that higher percentages of rubber yield a significant alleviation of vibration caused by repetitive and harmonic loads that are similar to those produced by passing trains. An addition of 5% by weight yields a reduction of 50% in the mean acceleration peak at one metre from the excitation source. The anisotropy of the mix is another key factor when evaluating the vibration behaviour of these mixes.