Development of a regional support spacing linear model for shallow room-and-pillar mines using large-scale numerical simulations

The room-and-pillar mining method is an effective technique used to extract ore from shallow tabular orebodies underground. Many hard rock room-and-pillar mines that operate in these orebodies face challenges due to extensive sub-horizontal shear structures and weak alteration layers. These geological features can lead to significant pillar failures if not appropriately managed. Designing effective pillar systems in these conditions requires optimising both in-panel and regional support strategies. While there has been much research on improving the design of in-panel pillars, guidelines for barrier pillars are still limited and rely mainly on ambiguous rules of thumb. To improve this, the paper proposes a new linear model for estimating the spacing of barrier pillars by using large-scale numerical simulations and multivariate regression analysis. The proposed model is applicable to mining depths up to 600 m within non-yield pillar systems and shows strong predictive performance, with a correlation coefficient of 0.86 and a coefficient of determination of 0.74. The applicability of the proposed simple linear model, which depends on mining depth and extraction ratio, was confirmed using a case study of a hard rock room-and-pillar mine and an arbitrary hypothetical mine. Its application proved to provide adequate regional mine support and enhanced stiffness of the entire pillar systems. Additionally, the model was compared to the rules of thumb. This method is an improvement over the rules of thumb, which may result in ore sterilisation and unreliable designs in certain circumstances. • A new linear model for estimating barrier pillar spacing in room-and-pillar mines is developed using large-scale numerical simulations and multivariate regression analysis. • The simple linear model, which depends on mining depth and extraction ratio, was tested using a case study mine and an arbitrary hypothetical mine. • The model was compared to the rules of thumb, and the results show a significant improvement by avoiding potential ore sterilisation and ensuring more reliable designs.