Numerical modeling of cave propagation and breakthrough timing

Authors: Cancino, C; Fuenzalida, M; Kamp, C

DOI https://doi.org/10.36487/ACG_repo/2435_D-07

Cite As:
Cancino, C, Fuenzalida, M & Kamp, C 2024, 'Numerical modeling of cave propagation and breakthrough timing', in Daniel Johansson & Håkan Schunnesson (eds), MassMin 2024: Proceedings of the International Conference & Exhibition on Mass Mining, Luleå University of Technology, Luleå, pp. 548-568, https://doi.org/10.36487/ACG_repo/2435_D-07

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Abstract:
New Afton Mine located 10 km outside Kamloops, Canada, started operating two separate caves, the West and East Caves (Lift 1), with production levels located approximately 600 m below the surface. The new B3 panel is located 160 m below and immediately to the west of Lift 1. Production at the B3 panel started mid-2021. A critical component of effective production for the B3 panel is successful cave propagation and breakthrough timing with Lift 1. Metallic and Optical Time Domain Reflectometry (MTDR and OTDR respectively) sensors were installed to assess cave initiation and propagation at B3. Also, seismicity was recorded, and cave tracker beacons were installed to assess flow behavior inside the muckpile. In 2022, a series of calibration stages over several months was completed to then provide refined numerical projections of the mobilized and yielded zones. The calibration of the B3 Cave was conducted using a hybrid modeling approach (FLAC3D-MassFlow) to simulate both the draw/flow and caving propagation to determine abutment stresses and cave loads induced on the extraction level as material was drawn. The model was calibrated with field data to better estimate cave propagation and the breakthrough timing with Lift 1. A proper prediction of the connection time was necessary to abandon the production level still active underneath Lift 1. This paper discusses the significance of using a strain-softening model (IMASS) with the ability to capture the correct mechanics of rock mass frictional strength mobilization, and the use of a hybrid FLAC3D-MassFlow modeling approach for a precise back-analysis of cave performance.

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