SciELO - Scientific Electronic Library Online

vol.109 número12Experimental 3-D modelling of surface subsidence affected by underground mining activitiesA semi-empirical kinetic model for the atmospheric leaching of a Ni-Cu converter matte in copper sulphate-sulphuric acid solution índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados



Links relacionados

  • Em processo de indexaçãoCitado por Google
  • Em processo de indexaçãoSimilares em Google


Journal of the Southern African Institute of Mining and Metallurgy

versão On-line ISSN 2411-9717
versão impressa ISSN 0038-223X

J. S. Afr. Inst. Min. Metall. vol.109 no.12 Johannesburg Dez. 2009




In situ measurements of Merensky pillar behaviour at Impala Platinum



B.P. WatsonI, II; J. KuijpersI; P. MiovskyIII

ICSIR Mining Technology, South Africa
IIUniversity of the Witwatersrand, South Africa
IIIImpala Platinum, South Africa




The Bushveld platinum group metal deposits in South Africa are the largest in the world. These deposits occur as two distinct stratiform tabular ore bodies and strike for many hundreds of kilometres. Mining is extensive, with depths ranging from close-to-surface to 2300 m. The mining method is a variation of planar open stoping. Crush pillars are widely used to support the open stopes. These pillars are designed to fail and the residual strength provides the required support resistance to stabilize the stoping excavations. This paper describes the in situ measurement, of stress within a Merensky pillar from Impala Platinum. These measurements were used to derive a stress-strain curve that includes pre and post failure behaviour. 2D FLAC modelling, with strain softening, was done to investigate how damage expands into the hanging- and/or footwall. Although the so-called 'squat' effect is always present, the modelling suggests that it does not dominate the pillar system behaviour at larger width to height ratios. Punching of the pillar into the hanging- and/or footwall increasingly controls the pillar system behaviour with larger width to height ratios. The paper investigates the behaviour of a system that incorporates the immediate hanging- and footwall, as well as the pillar itself.



“Full text available only in PDF format”




1. OZBAY, M.U. and ROBERTS, M.K.C. Yield Pillars in Stope Support. Rock Mechanics in Africa. SANGORM Congress. 1988.         [ Links ]

2. ROBERTS, D.P., CANBULAT, I., and RYDER, J.A. Design parameters for mine pillars: strength of pillars adjacent to gullies; design of stable pillars with w/h ratio greater than 6; optimum depth for crush pillars. SIMRAC GAP617 Final Report. SIMRAC. Johannesburg. 2002.         [ Links ]

3. WALSH, J.B. The effect of cracks on the uniaxial compression of rocks. J. Geophys. Res. vol. 70, no. 2, 1965. pp. 399-411.         [ Links ]

4. BRISTOW, J.R. Microcracks and the static and dynamic elastic constants of annealed and heavily cold-worked metals. Brittish J. Appl. Phys., vol. 11, 1960. pp. 81-85.         [ Links ]

5. KACHANOV, M. Effective elastic properties of cracked solids: critical review of some basic concepts. Appl. Mech. Rev., vol. 45, no. 8, 1992. pp. 304-335.         [ Links ]

6. GOODMAN, R.E., TAYLOR, R.L. and BREKKE, T. A model for mechanics of jointed rock. J. of Soil Mechs & Foundation Div., Proc. ASCE 94, SME3. 1968.         [ Links ]

7. POULOS, H.G. and E.H. DAVIS. Elastic solutions for Soil and Rock Mechanics. J Wiley& Sons. N. 1974.         [ Links ]

8. COMRO. MINSIM-D User's Manual, Chamber of Mines of South Africa, Johannesburg. 1981.         [ Links ]

9. Itasca consulting group, inc. Fast Lagrangian Analysis of Continua (FLAC) , Vers. 3.2. Minneapolis Minnesota USA. 1993.         [ Links ]

10. WATSON, B.P., KUIJPERS, J. NKWANA, M.M., and VAN ASWEGEN, L. The stress-strain behavior of in-stope pillars in the Bushveld Platinum deposits in South Africa. J. South African Inst. Min. and Met, vol. 107, 2007.         [ Links ]

11. YORK, G. Numerical modeling of the yielding of a stabilizing pillar/foundation system and a new design consideration for stabilizing pillar foundations. J. South African Inst. Min. and Met. vol. 98: 1998. pp. 281-293.         [ Links ]

12. PRANDTL, L. Zeit.Angew.Math. Mech. vol. T, no. 1, 1921. pp. 15-20.         [ Links ]

13. HERTZ, H. On the contact of rigid solids and on hardness, miscellaneous papers, Macmilan, London. 1986.         [ Links ]

14. COOK, N.G.W., HOOD, M., and TSAI, F. Observations of crack growth in hard rock loaded by an indenter. Int. J. Rock Mech. Min. Sci. & Geomech. Abstr., vol. 21, no. 2, 1984. pp. 97-107.         [ Links ]

15. DEDE, T. Fracture onset and propagation in layered media. MSc dissertation, University of the Witwatersrand, Johannesburg. 1997.         [ Links ]

16. ÖZBAY, M.U. AND RYDER, J.A. The effect of foundation damage on the performance of stabilizing pillars. J. South African Inst. Min. and Met., vol. 90, no. 2, 1990. pp. 29-35.         [ Links ]

17. WAGNER, H. and SCHÜMANN, E.H.R. The stamp-load bearing strength of rock. An experimental and theoretical investigation. Rock Mechanics, vol. 3, 1971. pp. 185-207.         [ Links ]

18. LENHARDT, W.A. and HAGAN, T.O. Observations and possible mechanisms of pillar associated seismicity at great depth. Proc. International Deep Mining Conference, Johannesburg, South Africa. J. South African Inst. Min. and Met. Symposium series S10, 1990. pp. 1183-1194.         [ Links ]

19. KORF, C.W. Stick and pillar support on Union Section, Rustenburg Platinum Mines. Association of Mine Managers of South Africa. 1978. pp. 71-82.         [ Links ]

20. ROBERTS, D.P., ROBERTS, M.K.C., JAGER, A.J., and COETZER, S. The determination of the residual strength of hard rock crush pillars with a width to height ratio of 2:1. J. South African Inst. Min. and Met. 2005. vol 105, pp. 401-408.         [ Links ]

21. WAGNER, H. Pillar design in coal mines. J. South African Inst. Min. and Met. January. 1980. pp. 37-45.         [ Links ]

Creative Commons License Todo o conteúdo deste periódico, exceto onde está identificado, está licenciado sob uma Licença Creative Commons