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The effect of a twin tunnel on the propagation of ground-borne vibration from an underground railway

The effect of a twin tunnel on the propagation of ground-borne vibration from an underground railway
The effect of a twin tunnel on the propagation of ground-borne vibration from an underground railway
Accurate predictions of ground-borne vibration levels in the vicinity of an underground railway are greatly sought after in modern urban centres. 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 paper presents a unique model for two tunnels embedded in a homogeneous, elastic fullspace. Each of these tunnels is subject to both known, dynamic train forces and dynamic cavity forces. The net forces acting on the tunnels are written as the sum of those tractions acting on the invert of a single tunnel, and those tractions that represent the motion induced by the neighbouring tunnel. By apportioning the tractions in this way, the vibration response of a two-tunnel system is written as a linear combination of displacement fields produced by a single-tunnel system. Using Fourier decomposition, forces are partitioned into symmetric and antisymmetric modenumber components to minimise computation times.

The significance of the interactions between two tunnels is quantified by calculating the insertion gains, in both the vertical and horizontal directions, that result from the existence of a second tunnel. The insertion-gain results are shown to be localised and highly dependent on frequency, tunnel orientation and tunnel thickness. At some locations, the magnitude of these insertion gains is greater than 20 dB. This demonstrates that a high degree of inaccuracy exists in any surface vibration prediction model that includes only one of the two tunnels. This novel two-tunnel solution represents a significant contribution to the existing body of research into vibration from underground railways, as it shows that the second tunnel has a significant influence on the accuracy of vibration predictions for underground railways.
0022-460X
6203-6222
Kuo, K.A.
49ce43a2-1952-4964-8eec-3018a74e0688
Hunt, H.E.M.
00743f03-05d5-4a74-bd25-96cd0679f808
Hussein, M.F.M.
3535c131-1710-4edc-a4a1-8fe67dee3f67
Kuo, K.A.
49ce43a2-1952-4964-8eec-3018a74e0688
Hunt, H.E.M.
00743f03-05d5-4a74-bd25-96cd0679f808
Hussein, M.F.M.
3535c131-1710-4edc-a4a1-8fe67dee3f67

Kuo, K.A., Hunt, H.E.M. and Hussein, M.F.M. (2011) The effect of a twin tunnel on the propagation of ground-borne vibration from an underground railway. Journal of Sound and Vibration, 330 (25), 6203-6222. (doi:10.1016/j.jsv.2011.07.035).

Record type: Article

Abstract

Accurate predictions of ground-borne vibration levels in the vicinity of an underground railway are greatly sought after in modern urban centres. 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 paper presents a unique model for two tunnels embedded in a homogeneous, elastic fullspace. Each of these tunnels is subject to both known, dynamic train forces and dynamic cavity forces. The net forces acting on the tunnels are written as the sum of those tractions acting on the invert of a single tunnel, and those tractions that represent the motion induced by the neighbouring tunnel. By apportioning the tractions in this way, the vibration response of a two-tunnel system is written as a linear combination of displacement fields produced by a single-tunnel system. Using Fourier decomposition, forces are partitioned into symmetric and antisymmetric modenumber components to minimise computation times.

The significance of the interactions between two tunnels is quantified by calculating the insertion gains, in both the vertical and horizontal directions, that result from the existence of a second tunnel. The insertion-gain results are shown to be localised and highly dependent on frequency, tunnel orientation and tunnel thickness. At some locations, the magnitude of these insertion gains is greater than 20 dB. This demonstrates that a high degree of inaccuracy exists in any surface vibration prediction model that includes only one of the two tunnels. This novel two-tunnel solution represents a significant contribution to the existing body of research into vibration from underground railways, as it shows that the second tunnel has a significant influence on the accuracy of vibration predictions for underground railways.

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More information

e-pub ahead of print date: 19 August 2011
Published date: December 2011
Organisations: Dynamics Group

Identifiers

Local EPrints ID: 354619
URI: http://eprints.soton.ac.uk/id/eprint/354619
ISSN: 0022-460X
PURE UUID: 04513b0e-c9a7-4da1-8835-6d9494d9b305

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Date deposited: 16 Jul 2013 14:03
Last modified: 08 Jan 2022 15:06

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Contributors

Author: K.A. Kuo
Author: H.E.M. Hunt
Author: M.F.M. Hussein

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