Hazard-aligned framework for interpreting cave geometry in block caving operations

Authors: Cuello, D; Orrego, C Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2645_07

Cite As:
Cuello, D & Orrego, C 2026, 'Hazard-aligned framework for interpreting cave geometry in block caving operations', in A van As, D Cumming-Potvin & J Wesseloo (eds), Caving 2026: Proceedings of the Sixth International Conference on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 1-18, https://doi.org/10.36487/ACG_repo/2645_07



Abstract:
In the management of large-footprint block cave mines, the interpretation of cave geometry is a fundamental input for assessing geotechnical hazards. However, a single definition of ‘cave shape’ is often insufficient to address the conflicting requirements of different geotechnical hazards. Operationally, a cave shape is commonly represented by the cave back, which is typically assumed to contain the mobilised zone or muckpile, while the space between the two, generated by drawing, may define a measurable airgap. This framework is appropriate for assessing connectivity-driven hazards, particularly airblast risk and airgap conditions. However, it does not capture the broader extent of yielding and rock mass degradation that may extend beyond the cave back. Consequently, when applied to seismic hazard assessment or surface breakthrough forecasting, it may lead to non-conservative interpretations. This paper presents an integrated interpretation framework that explicitly distinguishes between the mobilised zone and the broader zone of rock mass damage (yielding), interpreting each not as a single cave shape but as distinct geometrical surfaces derived from the available monitoring data. Drawing on 2 case studies from a large-footprint caving operation, the framework demonstrates that damage propagation frequently extends vertically and laterally well ahead of material mobilisation. A data hierarchy is proposed where direct indicators (e.g. marker consumption, cave trackers movement, and open-hole breakthrough) constrain the mobilised boundary, while indirect indicators (e.g. seismicity and passive tomography) define the yielded zone. In this context, ‘direct’ and ‘indirect’ denote whether an observation constrains the mobilised boundary itself or the surrounding rock mass damage, rather than whether it is physically observed. By formalising this distinction, operators can maintain conservative controls for airblast risk without underestimating the spatial footprint of seismic hazards and breakthrough, ensuring that hazard management strategies are aligned with the governing physical mechanisms of each risk.

Keywords: block caving, cave geometry interpretation, mobilised zone, yielded zone, geotechnical hazard management

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