ICGCM Papers:
Fundamental Research Studies
 
 
Enlightening Bolts: Using Distributed Optical Sensing to Measure the Strain Profile along Fully Grouted Rock Bolts
32nd International Conference on Ground Control in Mining
Enlightening Bolts: Using Distributed Optical Sensing to Measure the Strain Profile along Fully Grouted Rock Bolts
by
Andrew Hyett, Yieldpoint Inc., Kingston, CanadaBrad Forbes, Yieldpoint Inc., Kingston, CanadaAnthony (Sam) Js Spearing, Western Australian School of Mines, Kalgoorlie, Australia
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Author's Presentation PPT
[Conference] 32nd International Conference on Ground Control in Mining
[Price] Free  [Comments] 0
[Topical Area] Fundamental Research Studies
[Author] Andrew Hyett, Yieldpoint Inc., Kingston, CanadaBrad Forbes, Yieldpoint Inc., Kingston, CanadaAnthony (Sam) Js Spearing, Western Australian School of Mines, Kalgoorlie, Australia
[Abstract] 
Key Conclusions:
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A new rock bolt instrumentation technology based on Distributed Optical Sensing will be presented and evaluated in the laboratory. The principal advantages of the new technology over previous electronic approaches are: (i) Improved Resolution: improved spatial resolution that allows for the first time the detailed response of localized shear deformation to be monitored. (ii) Low cost/bolt : The instrumented bolts involve a standard optical fiber and are much cheaper than electronic bolts so allowing arrays of bolts to be cost effectively monitored. (iii) Intrinsically Safe: The instruments are inherently Intrinsically Safe since they are based on backscatter of light in an optical fiber. The potential for field application will be discussed.
Key Findings:
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For the first time, detailed strain profiles for rock bolt subjected to axial, shear and mixed-mode loading will be presented. Detailed strain profiles, based on >1000 strain measurements along the length of the bolt, indicate good agreement with theoretical predictions for axial loading. However, the results indicate that the shear behavior may be more complex than previously recognized.
Objective of the Paper:
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This new technology overcomes some important limitations of previous electronic instruments and provides the capability for >1000 points of strain determination along the bolt with reasonable levels of accuracy(better than +/- 10 microstrain). Laboratory test results will be presented that show the detailed load distribution along rock bolts subjected axial, shear and mixed mode tests.
Problem Statement:
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An important new instrumentation technology, Distributed Optical Sensing, which has already been used in other engineering disciplines, has been applied to the detailed examination of load distribution along rock bolts.