Authors: Haque, I; Hamman, JPE; Rohmadi, N; Santosa, G; Nguz Tshisens, J

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Haque, I, Hamman, JPE, Rohmadi, N, Santosa, G & Nguz Tshisens, J 2024, 'Stability assessment and ground support design for drifting through a cemented paste filled stope at the Big Gossan mine, Indonesia', in AB Fourie & D Reid (eds), Paste 2024: Proceedings of the 26th International Conference on Paste, Thickened and Filtered Tailings, Australian Centre for Geomechanics, Perth, pp. 505-514,

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This paper focuses on the process of developing a safe and stable drift through cemented paste fill (CPF) at PT Freeport Indonesia’s Big Gossan mine which allows access to the Kucing Liar mine. The access drift was designed with dimensions of 5.5 m width and 6.5 m height with a length of 20 m through a CPF stope. A risk assessment to develop a drift through a cemented paste filled stope indicated that a specific process of development and support sequence together with a stability analysis must be performed to ensure long-term stability. The analysis included in situ sampling and laboratory testing to determine the geomechanical material strength properties of the CPF. Stability analyses were conducted to determine the required thickness of in-cycle fibre reinforced shotcrete and mesh, pinned by friction bolts, as the main ground support system. The development operational stage was closely monitored through inspections and scanning to determine the effectiveness of the excavation process and ground support. In conclusion, this study successfully evaluated the feasibility of developing a drift through CPF, with effective ground support systems, to access the Kucing Liar mine safely. The risk assessment, development, and ground support sequence prior and after execution provided a robust foundation for design and safety considerations. This study serves as a valuable reference for engineers and mining professionals seeking to implement similar solutions in underground mining operations.

Keywords: Big Gossan, Kucing Liar, cemented paste fill, fibre reinforced shotcrete, risk register

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