Reola, CG, Lourence, PB, Bermas, JM & Dumangeng, DA 2023, 'Stabilising drawpoints for breccia stopes', in J Wesseloo (ed.), Ground Support 2023: Proceedings of the 10th International Conference on Ground Support in Mining, Australian Centre for Geomechanics, Perth, pp. 659-666, https://doi.org/10.36487/ACG_repo/2325_45
(https://papers.acg.uwa.edu.au/p/2325_45_Reola/)
Abstract: Production stopes at Didipio porphyry gold–copper mine, Philippines, are primarily comprised of two distinct types of rock mass: monzonite and breccia. The monzonite ground conditions are blocky and moderately strong. The breccia ground conditions are a classical, weak rock mass. Opening and stabilising the stope drawpoints in breccia presented challenges that require brow ground support revisions using a trialand-error approach. A combination of factors including span/geometry, lithological contacts, geological structures, and blast-induced damage all contribute to the overall brow and drawpoint performance.
This paper discusses the types of drawpoint support for breccia stopes using twin-strand, bulbed cable bolts and/or shotcrete-reinforced arches using Osro straps, pinned with friction bolts. Back analyses of recently mined-out stopes demonstrate improvements in brow stability when using shotcrete arches instead of relying entirely on cable bolts.

Keywords: ground support, brow support, drawpoint support, Osro straps, shotcrete arches, cable bolt