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Fast, non-destructive measurement of roof-bolt loads

undertaken to assess whether rock bolts have been installed properly. In the case of expansion-shell bolts, the tightening torque of the bolt nut tightened with a torque wrench is checked, and the load bearing capacity of the bolts is verified by pulling them out of the holes. Currently, Polish zinc, lead and copper mines commonly use roof-rock delamination detection systems. [ 5 , 22 ] For instance, the ‘Olkusz – Pomorzany’ mine has a detection system comprising five Bakelite plates or (like) Bakelite material and sleeves with two short rods pressed by the plates ( Fig

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