Authors: Sjöberg, J; Bolin, A; Sánchez Juncal, A; Wettainen, T; Mas Ivars, D; Perman, F
Editors: Potvin, Y
Conference: International Seminar on Design Methods in Underground Mining, 17-19 November, Perth
Published: Australian Centre for Geomechanics, Proceedings of the International Seminar on Design Methods in Underground Mining, pp.571-584, Perth
Orepasses are an integral part of the mining infrastructure in sublevel caving. As part of the investigations for potential continued deeper mining in the LKAB Malmberget mine, a study on orepass design has been completed. The initial portion of the work involved numerical modelling and rock mass strength calibration of observed orepass fallouts, and spalling failure in a ventilation shaft. The calibrated numerical model was subsequently used to study different orientations and locations of orepasses for a potential haulage level at depth.
The initial calibration work showed that a brittle material model — more precisely a cohesion-weakening frictionstrengthening (CWFS) model — was required to replicate both initiation and extension of stressinduced failure. A set of rock mass strength parameters was derived and further used in forward model prediction for planned orepasses. A large number of alternative scenarios were explored, in which orepass orientation and location, as well as material parameters, were varied. Orepass wear was simulated by creating a groove at the bottom of the orepass. Progressive spalling (stress-induced) failure was modelled in selected cases, by removing rock that was encapsulated by a contiguous shear band and the orepass wall in an iterative manner. The results are used in the design process for selecting suitable orepass locations.
Sjöberg, J, Bolin, A, Sánchez Juncal, A, Wettainen, T, Mas Ivars, D & Perman, F 2015, 'Input to orepass design — a numerical modelling study', in Y Potvin (ed.), Proceedings of the International Seminar on Design Methods in Underground Mining
, Australian Centre for Geomechanics, Perth, pp. 571-584.
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