Abstract

SEWNUN, D.; JOUGHIN, W.; ARMSTRONG, R.  and  COOPER, A.. Keyblock stability analysis of longhole stopes. J. S. Afr. Inst. Min. Metall. [online]. 2018, vol.118, n.3, pp.243-250. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2018/v118n3a7.

The orientations of discontinuity sets and major geological structures greatly influence the stability of an excavation. Excavations should therefore, where possible, be orientated such that major discontinuity sets and structures are considered, allowing the likelihood of rockfalls in a longhole stope to be kept to a minimum. The longhole stopes are non-entry excavations, which are remote cleaned to avoid exposure of personnel. However, excessive rockfalls can significantly influence productivity and cause damage to mining machinery. This paper presents a risk-based approach to design, where the failure potential of mining stopes for the Platreef mine was determined considering the influence of major structures. The probabilistic keyblock analysis software JBlock was used in this capacity. In this study, the failure potential of keyblocks was determined in JBlock for the longhole stopes of various proposed orientations, considering structural domains and a major geological fault which was identified across the project area. Results of the analysis indicated that stopes orientated sub-parallel to Platreefs major fault (Tshukudu Fault) resulted in the largest rockfalls. Overall, JBlock was used successfully as a design tool to assess the stability of the longhole stopes. Outcomes of the study have provided Platreef mine with valuable information that will assist in the decision-making process when finalizing stope orientations. This study therefore attempts to serve as a reference point for solutions to similar situations, with the objective that risk-based designs are called upon more frequently in the future.

Keywords : longhole stope; stope stability; keyblock; probabilistic analysis; JBlock.

        · text in English     · English ( pdf )