VIBRATION-ISOLATION PERFORMANCE OF FLOATING SLAB TRACK USED IN UNDERGROUND RAILWAYS

Floating slab track is a popular approach used to try to reduce vibration transmitted from underground railways into the surrounding soil and thence into nearby buildings. The rails are fixed to a concrete slab foundation which is supported on a resilient mounting, so isolating the track from the tunnel invert. However, the effectiveness of the vibration attenuation does not compare well with the simple mass-spring models typically used in the design of these tracks. This paper uses models of infinite length to investigate the performance of floating slab track in more detail. A track model constructed from an infinite series of repeating units is presented, each unit being two beams (for the rail and the slab) separated by elastic layers (for the resilient elements used in the track construction). An improved model consisting of an infinite slab beam mounted inside a tunnel of infinite length in soil of infinite extent is also presented.