Abstract

PORATHUR, J.L.; SEKHAR, S.; GODUGU, A.K.  and  BHARGAVA, S.. Stability analysis of a free-standing backfill wall and a predictive equation for estimating the required strength of a backfill material - a numerical modelling approach. J. S. Afr. Inst. Min. Metall. [online]. 2022, vol.122, n.5, pp.227-233. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/1544/2022.

Cemented backfilling has enabled underground hard rock mines to extract orebodies more safely with improved ore recovery. It is important to estimate the minimum required strength parameters for a backfill mix by optimizing the binder percentage to enable cost-effective and safe stoping operations. We conducted three-dimensional numerical modelling to study the effect of various stoping parameters on the stability of a free-standing backfill wall. A Mohr-Coulomb material model was used for the backfill material and the rock-fill interface. A strength reduction technique, excluding friction angle, was employed to arrive at a minimum stable strength value for the backfill. For a given combination of strength values, the stability state of the backfill wall could be demarcated using a displacement and yield zone tracking method. The numerical modelling results are compared to some earlier theoretical models. From the simulations, a predictive equation is developed to predict the required strength parameters for a backfill mix to ensure a stable free-standing wall. Examples are given of the successful use of the predictive equation at some underground hard rock mine sites in India.

Keywords : cemented backfill; underground stoping; backfill wall stability; numerical modelling; predictive equation.

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