Calibration of Numerical Model Applied to a Shear Zone Located on a Slope in an Open Pit Mine—Case History
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Abstract
The instability of a pit mine slope diagnostic caused by the slipping of a localized deep shear zone is described. The slope was designed on ultra basic, serpentine and metabasite rock formations with an angle varying from 40 to 45 de- grees. The perturbed slope zone was classified as RMR 12 and the non-perturbed zone as RMR 75. The boundary of these zones is defined as the shear zone. The pit slope was field mapped in detail and the mechanical properties of the rock were obtained through a laboratory test. The lab data were further processed using the RMR mechanical classifi- cation system. The Distinct Elements Code numerical modeling and simulation software was used to design the pit slope. The model was calibrated through topographic mapping of the points on the ground. The task of calibrating a numerical model is far from simple. Exhaustive attempts to find points of reference are required. The mechanical be- havior in function of the time factor is a problem that has yet to be solved. The instant deformation generated in the numerical model generated functions that can be compared with the deformations of quick shifts acquired in the topog- raphic monitoring. SMR is indeed more often recommended for Pit Slopes, though the fact that we have used RMR does not invalidate the classification for the modeling effect. The main parameters such as spacing, filling, diving direc- tion and continuity allow for compartmentalization of the modeled area. The objective of the modeling was not to pro- ject slopes because this massif was undergoing a progressive slow rupture. The objective of the modeling was to study the movement of the mass of rock and its progressive rupture caused by a shear zone.
- J. G. Ramsay, “Shear Zone Geometry a Review,” Journal of Structural Geology, Vol. 2, No. 1-2, 1980, pp. 83-89. doi:10.1016/0191-8141(80)90038-3
- Y. Hasuo, F. S. Magalhaes and A. F. Mangolin, “Applied Structural Geology,” 1992, pp. 363-382.
- P. A. Cundall, “Numerical Modeling of Jointed and Faulted Rock in Mechanics of Jointed and Faulted Rock,” A. A. Balkema, Rotterdam, 1990, pp 11-18.
- E. Gama and L. Borrher, “Efeito de uma zona de cisalhamento na estabilidade de um talude de minera??o”. In: IV Congresso Brasileiro de mina á ceu aberto e mina subterranea, Belo Horizonte. MG Brasil, 2006.
- IPT, “Relatório de Ensaios,” Instituto de Pesquisas Tecnologicas, Sama Minera??o, 1996.
- R. Cojean and S. Curtil, “Rapport d’Avancement des travaux de Thése,” ARMINES Centre de Geologie de L’Ingenieur, Paris, 1995.
- P. A. Cundall and R. D. Hart. “Development of Generalized 2-D and 3-D Distinct Element Modeling Programs for Jointed Rock,” Itasca Consulting Group, US Army Corps of Engineers, Itasca Consulting Group, 1985.
- D. Billaux, F. Dedecker and P. Cundall, “A Novel Approach to Studying Rock Damage: The Three Dimensional Adaptive Continuum/Discontinuum Code,” Proceedings of EUROCK 2004 & 53rd Geomechanics Colloquium, Ed. Schubert, 2004, pp. 723-728.
- E. M. Gama. “Rock Mechanics Applied to Mining,”. EEUFMG, Vol. 1, 2005.