ABSTRACT
Pillar stability guidelines have been presented by various authors in the past, based on a combination of empirical (mostly visual) observations from mining applications and simple numerical elastic stress indices or data from continuum plasticity analysis. There have been numerous developments in the past several decades in mechanistic classification (brittle spalling, effective continuum rockmass, structural control) and mechanism-appropriate modelling and design metrics. The design of pillar dimensions and spacing is a key factor in construction projects beyond mining including the engineering for deep geological repositories, hydroelectric power cavern complexes, underground storage, quarrying and other applications. These applications are situated in a variety of rockmass environments and at stress regimes from shallow to deep. In such applications, the geometry of the pillars and surrounding excavations deviates from the classic mine pillar scenario. This paper redefines design guidelines for pillar dimensioning based on numerical simulation results. It includes the consideration of rockmass deformation and yield (rockmass strength approach), brittle strength and damage behavior where appropriate. The investigation includes 3D FEM models with equivalent continuum networks.
