Floating Slab Railway Track for Isolation of Vibration: Models of Infinite Length

Abstract Vibration transmitted from underground railways into nearby buildings is an increasingly significant problem affecting high-value residential and commercial developments. Various forms of vibration isolation are used in underground railways, one of which is the ‘floating slab track’. Rails are fixed directly to a massive concrete slab which in turn rests on a resilient mounting (usually rubber bearings or steel springs) so isolating the track from the tunnel invert. The effectiveness of vibration attenuation does not compare well with the simple mass-spring models typically used in the design of floating slab track. This paper develops a model for floating slab track by conceptualising the track as two infinite beams (representing the rail and the concrete slab) separated by elastic layers representing the resilient elements used in floating slab track construction. A dynamic model for a finite-length unit of track is obtained from this physical model by the dynamic-stiffness-matrix method. A repeating unit method is utilised to create track models of infinite length from the finite track unit, an approach which much reduces the computation required. A concept of total force transmitted to the ground for a given set of inputs on the rail is developed, and the effect of various track parameters on the transmitted force is examined.