System and method for monitoring strain in roadway optical cable

Patent metadata

Field	Value
Publication number	US-2018266902-A1
Application number	US-201815981347-A
Country	US
Kind code	A1
Filing date	May 16, 2018
Priority date	Nov 18, 2015
Publication date	Sep 20, 2018
Grant date	—

Abstract

A system and method of delivering fiber optic communication service is provided. The method includes monitoring a strain signal generated by a strain-sensing optical fiber embedded in a roadway. The method includes comparing the strain signal to a predetermined allowable strain threshold of an optical communication cable associated with the strain-sensing optical fiber. The method includes relieving strain at a position along a length of the optical communications cable when the strain signal is determined to exceed the predetermined allowable strain threshold.

First claim

What is claimed is:

1 . A method of delivering fiber optic communication service comprising:
embedding a fiber optic cable within a channel formed within a roadway, the fiber optic cable including a communications optical fiber extending a length of the channel; embedding a strain-sensing optical fiber within the channel; determining strain experienced by the strain-sensing optical fiber from a strain signal generated by the strain-sensing optical fiber; comparing the determined strain to a predetermined allowable strain threshold; locating a roadway defect along the fiber optic cable when the determined strain exceeds the predetermined allowable strain threshold; and decreasing the strain experienced by the strain-sensing optical fiber and the fiber optic cable by modifying the roadway at the location of the roadway defect.

2 . The method of claim 1 , further comprising measuring a baseline strain of the strain-sensing optical fiber within one week of being embedded within the channel, wherein the predetermined allowable strain threshold is based at least in part on the measured baseline strain.

3 . The method of claim 1 , further comprising embedding a strain-isolated temperature sensing optical fiber within the channel.

4 . The method of claim 3 , further comprising determining temperature of the strain-sensing fiber by monitoring a temperature signal generated by the temperature sensing fiber, wherein determining the strain experienced by the strain-sensing fiber is based on both the determined temperature and the strain signal.

5 . The method of claim 4 , wherein the fiber optic cable includes an outer jacket surrounding the communications optical fiber, wherein the strain-sensing optical fiber and the temperature sensing optical fiber are located within the outer jacket of the fiber optic cable, wherein the communications optical fiber and the strain-sensing optical fiber are mechanically coupled to each other such that the strain experienced by the strain-sensing optical fiber relates to a strain experienced by the communications optical fiber.

6 . The method of claim 1 , wherein the predetermined allowable strain threshold is the strain associated with a total network optical signal attenuation of less than or equal to 2 dB.

7 . The method of claim 6 , wherein the predetermined allowable strain threshold is less than a recoverable strain limit of the fiber optic cable.

8 . The method of claim 1 , wherein decreasing the strain experienced by the strain-sensing optical fiber includes cutting portions of the roadway on both sides of the channel at the location of the roadway defect, and further comprising patching the cut portions of the roadway, wherein a strain experienced by the communications optical fiber relates to the strain experienced by the strain-sensing optical fiber, wherein decreasing the strain experienced by the strain-sensing optical fiber results in a decrease in the strain experienced by the communications optical fiber.

9 . The method of claim 8 , wherein cutting portions of the roadway on both sides of the channel includes extending each cut portion a length of at least 1 foot across the roadway defect, wherein the channel is formed in an asphalt or concrete material of the roadway, and the channel further comprises a polymeric material filling the channel and surrounding the fiber optic cable and the strain-sensing fiber.

10 . A method of monitoring a roadway-embedded fiber optic cable comprising:
monitoring a strain signal generated by a strain-sensing optical fiber embedded in a roadway; comparing the strain signal to a predetermined allowable strain threshold of an optical communication cable associated with the strain-sensing optical fiber; and relieving strain at a position along a length of the optical communications cable when the strain signal is determined to exceed the predetermined allowable strain threshold.

11 . The method of claim 10 , further comprising determining temperature of the strain-sensing fiber by monitoring a temperature signal generated by a temperature sensing fiber, wherein comparing the strain signal includes calculating an amount of strain experienced by the strain-sensing fiber, wherein calculating the amount of strain is based upon the temperature signal, and wherein both the strain signal and the temperature signal are determined by measuring an optical transmission property of optical signals transmitted along the strain-sensing fiber and the temperature sensing fiber.

12 . The method of claim 11 , wherein the predetermined allowable strain threshold is the strain associated with a roadway displacement of less than 10 mm.

13 . The method of claim 12 , wherein the predetermined allowable strain threshold is less than a recoverable strain limit of the optical communication cable.

14 . The method of claim 12 , wherein the optical transmission property of the optical signals of the strain-sensing fiber and the temperature sensing fiber is Brillouin scattering.

15 . The method of claim 10 , wherein relieving the strain comprises cutting portions of the roadway on both sides of the optical communication cable at a roadway defect causing the increased strain, and further comprising patching the cut portions of the roadway after the strain is relieved.

16 . The method of claim 15 , wherein each of the cut portions has a length of at least 1 foot and extends across the roadway defect.

17 . A roadway-based optical communication distribution system comprising:
a channel located beneath a surface of the roadway, the channel extending along a portion of a roadway; an optical communication cable located within the channel; a strain-sensing optical fiber located within the channel; and a strain monitor configured to monitor a strain signal generated by the strain-sensing optical fiber, wherein the strain monitor compares the strain signal to a predetermined allowable strain threshold of the optical communication cable, wherein the predetermined allowable strain threshold is less than a recoverable strain limit of the optical communication cable.

18 . The system of claim 17 , wherein the optical communication cable includes a cable jacket defining a lumen and an optical communication fiber located within the lumen, wherein the strain-sensing fiber is embedded in the cable jacket such that strain-sensing fiber experiences the strain experienced by the optical communication cable.

19 . The system of claim 18 , further comprising a strain-isolated temperature sensing optical fiber located within the lumen of the cable jacket.

20 . The system of claim 17 , wherein the predetermined allowable strain threshold is the strain associated with a total network optical signal attenuation of less than 2 dB.

Assignees

• Corning Optical Communications LLC

Inventors

• Logan Eric Raymond
• Miller Allen Michael

Classifications

• G01M5/0091

  by using electromagnetic excitation or detection · CPC title

• G01M11/086

  Details about the embedment of the optical fiber within the DUT · CPC title

• G01D5/3537

  Optical fibre sensor using a particular arrangement of the optical fibre itself · CPC title

• G01D3/028

  mitigating undesired influences, e.g. temperature, pressure · CPC title

• G01L1/242 Primary

  the material being an optical fibre · CPC title