The use of an innovative fiber optic methodology to capture the axial response of rib spacing and grout annulus effects on grouted rock bolts

The fully grouted rock bolt is used extensively as a ground support element within various underground projects. The physical testing of available research is largely focused on small embedment length samples as historic monitoring techniques and technologies have noted limitations as it pertains to capturing the mechanical behaviour of longer samples. To address this gap, the authors have developed a monitoring technique using fiber optics. This methodology captures the axial response by producing a continuous strain profile along the length of the rebar as well as the representative confining medium across a wide range of loading. This paper summarizes the results of a robust laboratory investigation to determine the impact of rib spacing arrangements as well as the size of grout annulus on bolt performance as it relates to rock bolt behaviour. The efforts of such results will be used to improve rock bolt support lengths for ground design purposes.