A Preliminary Investigation on Stochastic Discrete Element Modeling for Pillar Strength Determination in Underground Limestone Mines from a Probabilistic Risk Analysis Approach

摘要

Pillar strength determination has been one of the classic problems in underground mine design. A pillar is a load-bearing element left between excavations to provide global stability to the overall structure. Differing from other types of engineering structures, pillars are complex elements not only because of the stress fields that they are exposed but also because of their inherent anisotropy. Pillars are usually comprised of rock, specifically, in a rock mass scale where discontinuities are present. Therefore, their behavior not only depends on intact rock properties but also on the strength, distribution, and sizes of those discontinuities. Over the years, a series of analytical, empirical, observational, and numerical approaches have been proposed to estimate, determine, evaluate, and predict pillar strength and performance. However, many of these approaches do not consider site-specific conditions and generally consider "averaged" parameters in a deterministic way. This prevents mine operators from assessing the stability of the workings from a risk perspective. The integration of terrestrial laser scanning for rock mass characterization and stochastic discrete element modeling yields results that allow mining operators to predict site-specific rock fall hazards in underground operations. This work reviews existing pillar design approaches and focuses on those from a risk analysis basis. Additionally, a framework to estimate the pillar probability of failure based on the stochastic discrete element modeling approach is proposed.