THE INFLUENCE OF SLAB FOUNDATIONS ON GROUND-BORNE VIBRATION FROM RAILWAYS

The ever increasing urban population is leading to the exploitation of building sites, close to surface or underground railways, that were once deemed unsuitable because of the level of ground-borne vibration. An important design consideration is whether or not levels of perceptible vibration and/or re-radiated noise will be acceptable in the completed buildings. A fundamental question concerns to what extent the mass and stiffness of the building foundation influences these levels. This paper explores this question in relation to the commonly encountered, concrete slab foundation. Previous research has explored the influence of the coupling between a flexural plate and an elastic half-space on the free-surface displacements arising from surface Rayleigh waves. Here, a numerical wave-based approach is followed using the ElastoDynamics Toolbox in MATLAB. The case of an infinite, horizontal layer on top of an elastic half-space is considered, subject to incoming plane waves from a buried source. The paper highlights the significance of differences in the wave excitation when considering the construction of a "thick" slab foundation as a means of mitigating ground-borne vibration.