Geomechanical behaviour of underground excavations under squeezing conditions: damage mapping and multi-instrumental monitoring

Authors: de Almeida Pires Souza, B; Melo Oliveira, M Download Paper

DOI https://doi.org/10.36487/ACG_repo/2625_41

Cite As:
de Almeida Pires Souza, B & Melo Oliveira, M 2026, 'Geomechanical behaviour of underground excavations under squeezing conditions: damage mapping and multi-instrumental monitoring', 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. 1-13, https://doi.org/10.36487/ACG_repo/2625_41



Abstract:
Cuiabá mine, owned by AngloGold Ashanti and located in the Quadrilátero Ferrífero (Brazil), operates at depths of approximately 1,600 m, where increasing stress conditions impose significant geomechanical challenges. In this context, the Balancão (BAL) orebody has gained production importance while exhibiting pronounced squeezing behaviour, characterised by progressive and time-dependent deformation of the rock mass surrounding excavations. This study focuses on the main ramp of the BAL orebody, aiming to understand the geomechanical response of the rock mass and the performance of support systems as a function of mining-induced stress changes. The approach integrates multi-instrumental monitoring and field observations, including (i) systematic mapping of support damage, (ii) convergence measurements, (iii) multiple point borehole extensometers (MPBX), (iv) LiDAR scanning, and (v) geological and geomechanical characterisation. Deformation patterns were analysed in relation to the evolution of nearby stoping activities. Results indicate a spatially heterogeneous and time-dependent deformation response along the ramp. Convergence data reveal recurrent deformation phases, often delayed relative to mining activities, with alternating periods of acceleration and stabilisation. Support damage mapping demonstrates progressive degradation correlated with deformation intensity and proximity to active stopes. The observations highlight a transition from rigid to more ductile support strategies to accommodate ongoing squeezing conditions. The integration of monitoring data and field mapping provides a robust framework for interpreting deformation mechanisms and support response under deep mining conditions. The findings contribute to improving geotechnical understanding of support performance in squeezing environments and support more effective design and operational decision-making in similar underground settings.

Keywords: squeezing, underground geomechanics, geotechnical monitoring, numerical modelling, Cuiabá mine

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