Influence of Stope Excavation on Drift Convergence and Support Behavior: Insights from 3D Continuum and Discontinuum Models

Numerical modeling is an important tool in rock engineering. The choice for a particular numerical method is based on its capacity to represent the problem boundary conditions, the material behavior, and the pertinent rock mass failure mechanisms. It follows that there could be more than one numerical method suitable for a particular problem. In this respect, the selection of a particular method will be dictated by a series of technical and practical trade-offs. This paper addresses issues associated with the simulation of jointed rock masses and ground support by employing both continuum and discontinuum numerical methods. The focus is on the explicit simulation of a jointed rock mass and the implementation of ground support using a three-dimensional numerical code based on the distinct element method. 3DEC was used to generate continuum and discontinuum rock mass models, which were calibrated based on field instrumentation data from the George Fisher mine, in Australia. In particular, the investigation focused on the response of the ground support system, consisting of both reinforcement and surface support elements, to stress changes associated with the excavation of nearby stopes. The main difference between the constructed continuum and discontinuum 3DEC models was the representation of the rock mass at the location of the instrumented drift. In the continuum model, an equivalent continuum rock mass model, with the ubiquitous-joint (UJ) constitutive model, was used, whereas in the discontinuum model, joints were simulated explicitly. In this case study, it was observed that the adopted discontinuum modeling approach provided more realistic results than the continuum model with the UJ constitutive model, in terms of the drift convergence, support behavior, and depth of yielded zone due to the excavation of stopes near the instrumented section of the drift.