Mine haulage drifts are the primary access to the mining blocks of an orebody in a multilevel mining system of a tabular ore deposit. The stability and functionality of haulage drifts are thus crucial to the success of a mining operation. Drift instability could lead to serious consequences such as injuries, production delays and higher operational cost. In this paper, the performance of the haulage drift stability is evaluated on the basis of the primary rock support system comprising 1.8 m resin grouted rebars in the drift walls and 2.1 m long bolt in the back. Two failure criteria namely the extent of Mohr-Coulomb yield zones around the drift, and linear elastic brittle shear failure are adopted and compared, with respect to lower level and same-level mining and filling sequence in the vicinity of the haulage drift. The case study is one of the #1 Shear East zone of the Garson Mine in Sudbury, Ontario. Random Monte Carlo (RMC) technique, which has been previously established to assess the haulage drift stability, is employed in this investigation. The RMC technique is used in conjunction with finite difference modelling software FLAC for random assignment of model input parameters in the FLAC grid. Deterministic model results reveal the drift behaviour in terms of deformation (convergence) and mining-induced stress distribution. Comparison between the two different criteria is carried out to determine which method is most suitable in evaluating unsatisfactory drift performance. The results are presented in terms of probability of instability and categorized with respect to failure condition and mining step. It is shown that the brittle shear failure condition based on linear elastic response calls for enhanced support system at a later mining step than what Mohr-Coulomb yielding condition does. The paper presents a detailed discussion of the stochastic analysis results.

Underground mine developments, such as haulage drifts and cross cuts, play a vital role in providing access to ore extraction areas for mine production. The stability of mine developments is thus of crucial importance during the life of a mine plan. Many Canadian mines use longhole mining methods or one of its variants. These methods require access to the orebody through mine developments such as haulage drifts and cross cuts on multiple levels. This paper examines the stability of mine development access intersections with respect to the planned mining sequence. A case study, the #1 Shear East orebody at Vale’s Garson Mine in Sudbury, Ontario, is presented. A three dimensional, elastoplastic, finite difference model (FLAC 3D) was created for a development intersection situated 1.5 km below ground surface. The stability, or performance of the intersection, is evaluated in terms of the strength-to-stress ratio. The ratio threshold is set at 1.4 for temporary openings. Unsatisfactory performance is defined as a strength-to-stress ratio less than this threshold value. The performance of the intersection stability is evaluated at various modelled mining stages and the probabilistic method of analysis is then invoked to study the probability of unsatisfactory performance of the intersection. The results are presented and categorized with respect to probability, instability, and mining stage.

Mine haulage drifts are the primary access to the mining blocks of an ore body in a multi-level mining system of a tabular ore deposit. Drift instability could lead to serious consequences such as injuries, production delays and higher operational cost. A nonlinear, elastoplastic, two-dimensional finite element model is created to represent typical mining layout most commonly adopted in Canadian underground metal mines. Mohr-Coulomb yielding failure criterion is adopted with respect to lower and same-level mining and filling steps in the vicinity of the haulage drift. The haulage drift stability is evaluated on the basis of the primary rock support system comprising 1.8m resin grouted rebars in the drift walls and in the back. For the purpose of this study, the minimum anchorage length of rock support is taken as 30 cm (12-inch). The drift unsatisfactory performance occurs when the extent of yielding exceeds 1.5m resulting in insufficient anchorage length beyond the yield zone. The probabilistic method of analysis is then invoked to study the probability of unsatisfactory performance of the haulage drift. The results are presented and categorized with respect to probability, instability, and mining stage.

Haulage drifts are the primary access to the mining blocks of an ore body in a multi-level mining system of a tabular ore deposit. Drift instability could lead to serious consequences such as injuries, production delays and higher operational cost. Rockmass properties are significant geotechnical design input parameters. These parameters are never known precisely and always uncertainties associated with them. The stability of the haulage drift is examined through parametric study of a nonlinear, elastoplastic, two-dimensional finite element model representing typical mining layout most commonly adopted in Canadian underground metal mines. The parametric study examines the influence of footwall rockmass geomechanical properties (e.g., cohesion, friction angle, dilation angle and Young’s Modulus) and the mining depth (e.g., horizontal-to-vertical stress ratio). Stability indicators are defined in terms of displacement, stress and the extent of yield zones, which adopt as a basis for assessing the effect of different parameter on the stability of haulage drift.

Mine haulage drifts are the arteries of a mine. They are used for the transportation of blasted ore from the draw point to nearby ore pass or dumping point in deep underground mines. Thus, they must be remained functional during their service life. Otherwise, their instability could lead to serious consequences such as injuries, delay of production and increased operational cost. The objective of this paper is to evaluate the performance stability of mine haulage drifts with respect to mining step adopting numerical modeling of analysis. A two-dimensional, elastoplastic, finite difference code (FLAC 2D) is built for the purpose of this study. Haulage drift performance is evaluated using stability indicators and numerical modeling results are presented in terms displacement, stress and the extent of yield zones with espect to mining step.

Mine haulage drifts are the only stope access in sub-level stoping mining system. Thus, they must remain stable during their service life. Haulage drift instability could lead to serious consequences such as: production delay, damage to equipment, loss of reserves and high operational cost. The goal of this paper is the performance stability evaluation of mine haulage drifts with respect to mining sequence adopting different stochastic methods of analysis. A two-dimensional, elastoplastic, finite difference code (FLAC 2D) is used for this study. Stochastic analysis; adopting Point-Estimate Methods (PEMs), Monte-Carlo Simulation (MCS) and Random Monte-Carlo Simulation (RMCS) are then employed with the numerical modelling to tackle the inherent uncertainty associated with rockmass properties. Then, the probability of instability at last mining step (e.g., after excavating stope 3) is estimated for haulage drift side walls and roof. The stability indicators are defined in terms of displacement, stress and the extent of yield zones, which are adopted as a basis for assessing the performance stability of haulage drift. The stochastic results are presented and compared in terms of probability of occurrence at last mining stage (e.g., after excavating stope 3) adopting displacement/convergence criterion.