In Situ Fibre-Optic Instrumented Rebar


Mr Garrett Snell ( - University of Saskatchewan), Mr Evan Kuley ( - University of Saskatchewan), Prof Doug Milne ( - University of Saskatchewan)

An emerging technology often called distributed optical sensing allows for strain measurement using fibre-optics. The technology uses Rayleigh scattering to measure strain at 0.7 mm increments along a several metre length of fibre-optic cable. The fibre-optic has been installed along the length of rebar rockbolts. The rockbolts were then installed by resin-grouting at various potash mines in Saskatchewan. The procedure for bolt installation and handling of the read-out unit will be discussed. Potash deforms a significant amount and the corresponding stress and strain response within the rebar can be determined with the fibre-optic instrumentation. Multiple readings were taken of the rockbolts as deformation progressed. The results were processed and the evolution of deformation within the rebar can be seen. The tensile, shear, and bending behaviour that a rockbolt can undergo is quite complex, but the fibre-optic instrumented bolt can measure this 3-dimensional behaviour. Knowing the deformation profile of the rebar rockbolt provides new insight into their performance. Distributed optical sensing can allow engineers to make more accurate evaluations of ground support requirements.