Snell, G, Kuley, E & Milne, D 2017, 'A laboratory-based approach to assess rockbolt behaviour in shear', in M Hudyma & Y Potvin (eds), Proceedings of the First International Conference on Underground Mining Technology
, Australian Centre for Geomechanics, Perth, pp. 45-54, https://doi.org/10.36487/ACG_rep/1710_02_Snell
Epoxy-bonded rebar is commonly used to support the roof of an underground potash mine. The rebar is often loaded in tension, but in certain circumstances, the potash can load the rebar in shear or by a combination of tension and shearing.
Rebar failure due to tension has been studied previously and is well understood. A laboratory test procedure has been developed to help quantify rebar shear behaviour. The rebar is tested by bonding it in three segments of steel pipe and applying a lateral load to the centre segment.
These tests isolate the rebar–epoxy interaction from the highly variable effect of the surrounding potash. The test method also allows for an easy and controlled comparison of different sizes of rebar, grades of rebar steel, and aperture between the pipe sections; all of which can significantly affect the behaviour of rebar in shear.
The data gathered during each test includes the load and displacement. However, distributed optical strain sensing is also being used, which allows for strain measurements at 0.5 mm resolution along the length of the rebar. This technology allows for detailed insight into rebar behaviour.
The International Minerals Innovation Institute (IMII), PotashCorp, The Mosaic Company, Agrium Inc., as well as Natural Sciences and Engineering Research Council of Canada (NSERC) are sponsoring this research project.
Keywords: potash, shear, rebar, fibre-optic
Aziz, N, Pratt, D & Williams, R 2003, ‘Double shear testing of bolts’, Proceedings of Coal 2003: Coal Operators' Conference, University of Wollongong, Wollongong, and Australasian Institute of Mining and Metallurgy, Melbourne, pp. 154–161.
Bjurstrom, S 1974, ‘Shear strength of hard rock joints reinforced by grouted untensioned bolts’, Proceedings of the 3rd International Conference of the International Society for Rock Mechanics, International Society for Rock Mechanics, Lisbon, pp. 1194–1200.
Dight, P 1982, Improvements to the Stability of Rock Walls in Open Pit Mines, PhD thesis, Monash University, Melbourne.
Dube, S 1995, A Laboratory Study on the Behaviour of Cable Bolts Subjected to Combined Tensile and Shear Loads, MSc thesis, Queen's University, Kingston.
Farmer, I 1975, ‘Stress distribution along a resin grouted rock anchor’, International Journal of Rock Mechanics and Mining Sciences and Geomechanics, vol. 12, pp. 347–351.
Ghadimi, M, Shahriar, K & Jalalifar, H 2014, ‘Analysis profile of the fully grouted rock bolt in jointed rock using analytical and numerical methods’, International Journal of Mining Science and Technology, vol.4, no. 5, pp. 609–615.
Jalalifar, H, Aziz, N & Hadi, M 2006, ‘The effect of surface profile, rock strength and pretension load on bending behaviour of fully grouted bolts’, Geotechnical and Geological Engineering, vol. 24, no. 5, pp. 1203–1227.
Neely, D 2014, Failure Mechanism of Resin Anchored Rebar in Potash, MSc thesis, University of Saskatchewan, Saskatoon.
Nemcik, J, Ma, S, Aziz, N, Ren, T & Geng, X 2014, ‘Numerical modelling of failure propagation in fully grouted rock bolts subjected to tensile load’, International Journal of Rock Mechanics & Mining Sciences, vol. 71, pp. 293–300.
Pellet, F & Egger, P 1996, ‘Analytical model for the mechanical behaviour of bolted rock joints subjected to shearing’, Rock Mechanics and Rock Engineering, vol. 29, no. 2, pp. 73–97.
Samiec, D 2012, ‘Distributed fibre-optic temperature and strain measurement with extremely high spatial resolution’, Optical Metrology Photonik International, pp. 10–13.
Spang, K & Egger, P 1990, ‘Action of fully-grouted bolts in jointed rock and factors of influence’, Rock Mechanics and Rock Engineering, vol. 23, no. 3, pp. 201–229.
Stimpson, B 1987, ‘An analytical method for determining shear stiffness of an inclined grouted bolt installed across an open discontinuity’, International Journal of Mining and Geological Engineering, vol. 5, no. 3, pp. 299–305.