Monitoring transport network infrastructure

• US 9,561,812 B2
• Filed: 02/22/2013
• Issued: 02/07/2017
• Est. Priority Date: 02/24/2012
• Status: Active Grant

• Current Assignee: Optasense Holdings Limited (Luna Innovations, Inc.)
• Original Assignee: Optasense Holdings Limited (Luna Innovations, Inc.)
• Inventors: Godfrey, Alastair
• Primary Examiner(s): Kwok, Helen
• Application Number:
  US14/380,130
• Publication Number:
  US 20150013465A1
• Time in Patent Office: 1,446 Days
• US Class Current: 1/1
• CPC Class Codes: B61L 1/166 Optical
• CPC Class Codes: B61L 23/04 for monitoring the mechanical state of the route
• CPC Class Codes: B61L 23/044 Broken rails
• CPC Class Codes: B61L 23/045 Rail wear
• CPC Class Codes: B61L 23/047 Track or rail movements
• CPC Class Codes: B61L 23/048 Road bed changes, e.g. road bed erosion
• CPC Class Codes: B61L 27/53 for trackside elements or systems, e.g. trackside supervision of trackside control system conditions
• CPC Class Codes: G01M 5/0025 of elongated objects, e.g. pipes, masts, towers or railways G01M5/0058 takes precedence
• CPC Class Codes: G01M 5/0033 by determining damage, crack or wear
• CPC Class Codes: G01M 5/0066 by exciting or detecting vibration or acceleration vibration testing of structures G01M7/00
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection
• CPC Class Codes: G01N 29/04 Analysing solids using acoustic emission techniques G01N29/14

Abstract

The present invention relates to conditions monitoring of structures forming part of a transport network, e.g. structural health monitoring of structures, especially tunnels by performing distributed acoustic sensing (DAS) on at least one optical fiber (104) deployed so as to monitor the structure (206) and detecting and analyzing the acoustic response to movement of traffic (205) on the network in the vicinity of the structure to detect the acoustic response (303, 304) of the structure. The acoustic response of the structure is then analyzed to detect any change in condition.

Claims

1. A method of condition monitoring of a structure forming part of a transport network comprising:

performing distributed acoustic sensing on one or more optical fibres deployed to monitor said structure to provide a measurement signal from each of a plurality of acoustic sensing portions;

analysing the measurement signals generated from movement of traffic on the transport network in a vicinity of said structure to identify acoustic signals associated with said structure; and

analysing said acoustic signals associated with said structure to provide an indication of any changes in condition of said structure;

wherein analysing said acoustic signals associated with said structure comprises identifying acoustic waves propagating in the structure and analysing the propagation speeds of acoustic waves in the structure.

2. A method as claimed in claim 1 wherein analysing said acoustic signals associated with said structure comprises comparing the acoustic signals with previously acquired acoustic signals.

3. A method as claimed in claim 1 comprising identifying any discontinuities in acoustic waves propagating in the structure.

4. A method as claimed in claim 1 comprising identifying acoustic waves propagating at different speeds in the structure.

5. A method as claimed in claim 1 wherein the acoustic signals associated with said structure comprise acoustic signals detected by the sensing portions before and/or after the traffic movement past the relevant sensing portion.

6. A method as claimed in claim 1 wherein the acoustic signals associated with said structure comprise a low frequency response.

7. A method as claimed in claim 1 further comprising performing distributed acoustic sensing on said one or more optical fibres to track the movement of traffic on the transport network.

8. A method as claimed in claim 7 wherein at least part of said one or more optical fibres is deployed along a path of the transport network.

9. A method as claimed in claim 8 wherein a first optical fibre of said one or more optical fibres has at least a first section deployed along the path of the transport network and at least a second section deployed to monitor said structure.

10. A method as claimed in claim 9 wherein the second section of the first optical fibre is attached to the structure.

11. A method as claimed in claim 1 wherein the transport network is a rail network.

12. A method as claimed in claim 11 wherein said structure comprises a tunnel.

13. A method as claimed in claim 12 wherein said one or more optical fibres comprises at least one optical fibre deployed alongside a rail track running through the tunnel.

14. A method as claimed in claim 13 wherein said structure comprises the rail track.

15. A method of condition monitoring of a structure forming part of a transport network, the method comprising:

receiving a plurality of measurement signals acquired by a one or more distributed acoustic sensors having one or more optical fibres deployed to monitor said structure;

analysing the measurement signals generated from movement of traffic on the transport network in a vicinity of said structure to identify acoustic signals associated with said structure; and

analysing said acoustic signals associated with said structure to provide an indication of any changes in condition of said structure;

wherein analysing said acoustic signals associated with said structure comprises identifying acoustic waves propagating in the structure and analysing the propagation speeds of acoustic waves in the structure.

16. A distributed acoustic sensing system comprising:

an interrogator unit for, in use, performing distributed acoustic sensing on one or more optical fibres deployed to monitor a structure of a transport network to provide a measurement signal from each of a plurality of acoustic sensing portions; and

a processor configured;

to analyse the measurement signals generated from movement of traffic on the transport network in a vicinity of said structure to identify acoustic signals associated with said structure; and

analyse said acoustic signals associated with said structure to provide an indication of any changes in condition of said structure by identifying acoustic waves propagating in the structure and analysing the propagation speeds of acoustic waves in the structure.

17. A distributed acoustic sensing system according to claim 16 comprising at least one optical fibre deployed to monitor the structure.

18. A distributed acoustic sensing system according to claim 17 wherein at least part of said at least one optical fibre is deployed along a path of the transport network.

19. A distributed acoustic sensing system according to claim 18 wherein the transport network is a rail network.

20. A distributed acoustic sensing system according to claim 19 wherein the system is configured to monitor the condition of one or more tunnels on the transport network.