This paper presents an assessment in terms of the influence that blast damage can have over rock pillars and the behavior of rock mass using 3D numerical modelling. The utilization of this approach enables the calibration of model parameters and highlights the framework concerning limit loads and deformations that can occur in production drifts, as well as their association with pillar stability. Its relevance becomes substantial during the construction of underground mines and when utilized for decision-making in project design, where the impact of blasting plays a crucial role in achieving high-quality engineering work.
During the extraction level construction of an underground mine by Block Caving or Sublevel Caving that will include drifts and galleries arrangements or openings, the blasting effect on the strength and deformability of the pillar is quite significant. The excavations proximity develops some relaxation or induced damage that if not considered, will have relevant implications on the behavior of the rock mass in the short and long term. Although some examples have been found where the impact of this type of damage is exposed (Jessu et al, 2018), these do not take into consideration the inherent shape of the tunnels, their arrangement, or the intersections between them generated, as is the case of the pillars formed in large-scale underground mining.
While other assessments, such as the one conducted by Renani & Martin (2018), take into account the intersection of drifts, they do not consider the induced effects of blasting damage on the strength and deformability of the pillar. The present paper examines the level of impact that considering such damage has when utilizing Hoek & Brown's (2002) approach, along with the recommendations that were issued prior to the 2018 update. The assessment specifically applies to pillars frequently employed in large-scale underground mining methods like Panel Caving and Sublevel Caving. It is important to note that this paper solely addresses geotechnical stability concerns and does not delve into issues related to mining method geometries or support systems.
