Abstract

Accurate predictions of ground-borne vibration levels in the vicinity of an underground railway are greatly sought after in modern urban centers.

Yet the complexity involved in simulating the underground environment means that it is necessary to make simplifying assumptions about this system. One such commonly-made assumption is to ignore the effects of neighbouring tunnels, despite the fact that many underground railway lines consist of twin-bored tunnels, one for the outbound direction and one for the inbound direction.

This talk will examine this assumption through the development of a novel model for two tunnels embedded in a homogeneous, elastic fullspace. The magnitude of the interactions between the tunnel will be quantified as a function of frequency, tunnel orientation, and tunnel thickness. The second tunnel will be shown to have a significant influence on the predicted vibration levels, leading to the recommendation that the twin-tunnel model be used for underground railway vibration predictions.