The Design of Improved Optical Fibre Instrumented Rockbolts

Developing an improved understanding of the interaction between the immediate roof and the rockbolts is fundamental in obtaining an effective roof support system. Effective instrumentation along the full length of fully grouted rock bolts would provide the required understanding, which in turn could improve the rock related safety in the underground mines. The rock bolt sensing technology has rapidly developed in the last decade, where the instrumentation has changed from short electrical strain gauges to optical strain and shape sensing using more than 2 slots (which used to be the standard). In addition, the instrumentation has been increased from two orthogonal slots to three or four. With these recent advances of the technologies, there lies a challenge in analysing and understanding the new type of data and in effectively adopting the new technology into the underground mines. This paper deals with the challenges of instrumenting rock bolts with fibre optics and presents techniques for improving the existing technology. Furthermore, it includes a prototype design for an effective implementation of this technology to better suit the harsh underground environment.