The Effect of Shearing on Fully-grouted Rebar Rock Bolts in Saskatchewan Potash Mines

Abstract

Reinforcing bar (rebar) is a common method of ground support in underground potash mines in Saskatchewan. The rebar is anchored into the potash rock to provide support using resin and the system is referred to as a fully-grouted rebar rock bolt. The rebar can be subjected to tensile deformation and shear deformation due to the geomechanical properties of potash and the presence of relatively weak interbedded clay seams. Although the tensile deformation of the rebar is well understood, shear deformation is not.

This research project focussed on determining the magnitude of shear plane displacement that a rebar rock bolt can withstand before failure. The objectives of this research were achieved using a combination of laboratory testing, field testing, and in situ instrumentation for monitoring field behaviour.

Ultimately, a design chart was generated to estimate the shear displacement capacity of rebar rock bolts under varying shear plane apertures. This chart is meant to help mine engineers determine re-bolting requirements to maintain safe drift access for mine personnel.