Abstract

Rockbolts are commonly used to hold fractured rock to the ceilings of drifts. After determining that no economical technology exists for measuring the load on these bolts, a researcher in McGill University’s Mining Engineering Department is proposing a new load measuring device called SAFEBOLT. This tool consists of an electrical resistance strain gauge enclosed in the head of a rockbolt and connected by cable to a display module. Load measuring devices (mechanical and resin) were installed and tested in three mines. The actual conditions of use allowed the researcher to increase the strength of the bolts. SAFEBOLT technology has proven reliable and easy to use, although it has certain limitations: its margin of error is 0.05 tonnes, and the bolt angle in relation to the wall must not exceed 10 degrees.