Prediction of low frequency vibration propagation from operating rail tunnels

Abstract

Predicting the propagation of vibrations from rail tunnels is important for quantifying and mitigating the environmental impacts of operating railways. In the general case, vibrations propagating from rail tunnels are attenuated by material damping and geometric effects. Often these effects are aggregated in empirical or numerical models which offer little insight into the physical behaviors that are involved and may be limited in terms of their applicability according to frequency range and tunnel-receiver geometry. This paper examines the aspects of low frequency vibration propagation from rail tunnels that are of relevance to predicting tactile vibration impacts and the influence of operating railway vibrations on sensitive imaging equipment. Fundamental geometric considerations and numerical models are used to determine the influence of pseudo-static effects, source-receiver geometry, layered ground and material damping effects, and the relationship between average and maximum vibration levels that are dependent upon source-receiver distance.