Improving Rock Pillar Stability Guidelines Through Detailed Numerical Investigation

Abstract

Abstract Pillar stability guidelines have been presented by numerous authors in the past, based on a combination of empirical observations (mostly visual) from mining applications and simple numerical (elastic or simple continuum plasticity) models. In many cases, the resulting design limits for pillar dimensioning are presented as universal for all rockmass conditions and stress regimes. There have been numerous developments in the past decades in mechanistic classification (brittle spalling, effective continuum rockmass, structural control) and mechanism-appropriate modelling and design metrics. These new tools and paradigms for rockmass behaviour allow for a modelling-based revision of the empirical guidelines from the past century that still form the basis of many performance critical designs. This paper includes the consideration of rockmass deformation and yield (rockmass strength approach), brittle strength, and damage behaviour where appropriate. This paper presents correlations for residual GSI and the effects of Hoek-Brown dilation on pillar behaviour. The investigation includes generating 3D FEM synthetic pillar models with equivalent elastic and plastic continuum.