Yielding steel sets for high-convergence conditions in block caving: design basis and expected performance at Chuquicamata underground mine

Authors: Castro, D; Barindelli, G; Fumeron, J; Ottesen, M; Trigo, C Download Paper

DOI https://doi.org/10.36487/ACG_repo/2625_15

Cite As:
Castro, D, Barindelli, G, Fumeron, J, Ottesen, M & Trigo, C 2026, 'Yielding steel sets for high-convergence conditions in block caving: design basis and expected performance at Chuquicamata underground mine', in D Cumming-Potvin & J Wesseloo (eds), Ground Support 2026: Proceedings of the 11th International Conference on Ground Support in Mining, Australian Centre for Geomechanics, Perth, pp. 1-14, https://doi.org/10.36487/ACG_repo/2625_15



Abstract:
Underground excavations developed under high-stress and poor rock mass quality frequently experience severe convergence, compromising the performance of conventional support systems. This is particularly relevant in block caving operations, where stress redistribution and progressive damage can induce large deformations around infrastructure located in production levels. At Chuquicamata underground mine (Chile), adverse geomechanical conditions characterised by highly fractured rock masses, low Q-values, and significant stress concentrations led to the implementation of yielding steel sets as a specialised support system. These systems were selected to accommodate large displacements while maintaining load-bearing capacity, unlike conventional rigid support that tends to fail under squeezing conditions. This paper presents the geological and geotechnical framework that justified the adoption of yielding support, including rock mass characterisation, expected deformation mechanisms, and limitations observed in traditional support schemes. The design approach is described, focusing on the mechanical behaviour of yielding steel sets, which are engineered to allow controlled deformation in both axial and lateral directions through predefined yielding elements. Their structural response is discussed in terms of load–displacement capacity, energy absorption, and interaction with surrounding rock. Additionally, the technical basis used to estimate their performance is presented, including analytical considerations and numerical analysis of expected convergence scenarios. Although the system has been installed in selected sectors, it has not yet been subjected to operational loading conditions, as the corresponding mining areas are not yet in production. Therefore, this work emphasises the design philosophy and expected performance envelope, establishing a baseline for future field validation. The study contributes to the understanding of yielding support systems as a viable alternative for managing large deformation demands in deep and high-stress mining environments.

Keywords: support, rock mechanics, yielding steel arches, dynamic support systems, squeezing, underground mining

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