Nonlinear rock mass behaviour and application to stability of underground haulage drift

Numerical methods of analysis such as the finite element method and finite difference method have seen increasing use in recent years as tools for geomechanical mine design to predict problems of ground caving and failure. As a result of recent advances in computer technology, it is now possible to handle large-scale problems involving complex material and geometric nonlinearities at an affordable computational cost. The scope of this study is the stability of underground mine haulage drifts associated with sublevel stoping method with delayed backfill. This is one of the most popular mining methods today in Canadian underground metal mines. In this method, blasted ore is mucked with load-haul-dump vehicles and transported to the nearest dump through a nearby haulage drift. Therefore, it is crucial in a mining operation that a haulage drift remains functional during the life of the stope.; This study is focused on studying the interaction between the haulage drift and nearby mining activity. The stability of the haulage drift is examined through a detailed parametric study of a finite element model representing typical mining layout most commonly adopted in Canadian underground metal mines. The model parametric study examines the influence of critical factors such as the stope mining sequences, mining depth and the distance between the stope and the haulage drift. The model is set up for nonlinear behaviour of the rock mass taking into account elastoplasticity of the rock mass and non-associated plasticity using Mohr Coulomb and Drucker Prager yield functions. Stability indicators are defined in terms of displacement, stress and the extent of yield zones. These indicators serve as a basis for assessing the effect of different parameters on the stability of the haulage drift.; From the model parametric study, it is found that stope mining causes a lateral movement of the entire drift. The severity of such movement is increased with shorter distance between the stope and haulage drift. Of all mining sequences examined, same-level mining is the most critical step. It is also found that more yield zones develop around the haulage drift as the mining depth increases and as distance between haulage drift and the stope decreases.; A 3-centre arc drift is compared with a rectangular one of the same cross sectional area. It is found that the 3-centre arc drift shape is more stable. This study also demonstrates that the nonlinear elastoplastic analysis gives more realistic results than traditional linear elastic analysis in terms of stress and displacement behaviour of the haulage drift.