The control of ground-borne vibrations from railway traffic by means of continuous floating slabs

This paper deals with the effectiveness of a floating slab track for the control of ground-borne vibrations generated by rail transportation systems. The effectiveness is studied by means of a three-dimensional numerical model for the prediction of railway induced vibrations that fully accounts for the interaction between the train, the track and the soil. The incorporation of a resilient mat in a slab track system results in a resonance phenomenon that is determined by the mass of the slab track and the resilience of the mat. At frequencies higher than the slab resonance frequency, the concrete slab uncouples from the underlying soil and the transfer of vibrations is reduced. The effective reduction in the free field, however, is highly dependent on the dynamic characteristics of the slab and the soil. In the case where the phase velocity of the bending waves in the slab is higher than the phase velocity of the Rayleigh waves in the soil, the radiation of waves into the free field is modified. As a result, the reduction of the free field vibrations depends on the angle between the track and the line between the source on the track and the receiver in the free field. In the case where the phase velocity of the bending waves in the slab is much lower than the phase velocity of the Rayleigh waves, a more uniform reduction of the free field response is obtained.