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7.
FIRST PILOT IN SITU PROGRAM
The main objective of the pilot in situ program was to validate the SAFEBOLT technology for
the underground environment, and to improve the instrument design in light of the experience
gained and feedback obtained from the mines. The first set in situ trials involved the installation
of SAFEBOLT instrumented rockbolts and rebars at three underground operating mines in
Quebec, namely Niobec, Doyon and Bousquet. This pilot installation also involved the training
of mine personnel on how to monitor the axial loads on the bolts. Figure 17 illustrates the
mining application that was targeted at the mines. As can be seen, the bolts were installed near
the face of an advancing drift. This is an application where the instrumented bolts were expected
to see load variation with face advance. Also, it was foreseeable that the instrumented bolts
would be subjected to severe conditions due to their proximity to the blasting face.
Instrumented
rockbolts
Face advance
Cut 1
Cut 2
Load distribution
Figure 17: Application of SAFEBOLT technology in a drift development
7.1
Niobec Mine
Figure 18 shows the cross section of the drift on Level 900 at Niobec mine, where the pilot
installation program took place. Six ¾” (19mm)-diameter instrumented rebars were prepared.
The rebars are 5-foot long and have a yield load of 8.95 tonnes (20,040 lbs).
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