A power-flow based investigation into the response of buildings to ground-borne vibration from underground railways

Abstract

Ground-borne vibration in buildings is a growing problem in crowded cities due to the pressure to build ever closer to underground railway tunnels. Despite advances in numerical models for the prediction of ground-borne vibration, it is yet unclear how effective deep piled foundations are at mitigating the vibration transmitted into a building compared to shallow foundations, such as footings. The power-flow insertion gain is used as a measure of the building's overall vibration performance when piles, rather than footings, are included in the foundation. The tunnel-foundation system is based on the pipe-in-pipe model of a longitudinally invariant tunnel coupled to a boundary-element model of the foundation using an iterative wave-scattering approach. The initial theoretical study presented in this paper shows that piles generally attenuate the vibration levels in a benchmark building compared to footings. It is also shown how a simplified model for a tall building, based on a series of individual dashpots, can account for the modification of the foundation vibration field when the building is constructed.