The impact of pore pressure boundary conditions in stope backfilling models

Authors: Doherty, JP Download Paper

DOI https://doi.org/10.36487/ACG_rep/1404_07_Doherty

Cite As:
Doherty, JP 2014, 'The impact of pore pressure boundary conditions in stope backfilling models', in Y Potvin & T Grice (eds), Mine Fill 2014: Proceedings of the Eleventh International Symposium on Mining with Backfill, Australian Centre for Geomechanics, Perth, pp. 113-120, https://doi.org/10.36487/ACG_rep/1404_07_Doherty



Abstract:
Fully coupled numerical models for simulating mine backfill typically assume zero pore pressure conditions at the top of the fill. This implies full saturation of the fill mass. In this paper, Gibson's solution is examined to identify situations where this use of zero pore pressure boundary conditions is likely to be unrealistic. A model that is able to capture phreatic draw down and fill desaturation is then briefly described. The model also accounts for changes in strength, stiffness and permeability due to cement hydration. An example two−dimensional simulation of stope backfilling is then presented. The analysis is conducted assuming full saturation and zero pore pressure boundary conditions, as well as a more realistic simulation that accounts for desaturation. It is shown that phreatic draw down and fill desaturation have a significant impact on pore pressure within the fill mass and barricade loads.

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