The development of a software code for simulation of the impact of mining layouts on stress fields and rock mass deformation or displacement is a demanding process, even after a mathematical framework for the code has already been established. The initial version of the limit equilibrium code, TEXAN, has been expanded to include features such as off-reef structures (bedding planes and faults) as part of a larger research project at the University of Pretoria that has the aim to derive an appropriate mine design criterion for deep-level, seismically active mines. Deep-level mining environments are characterized by a highly discontinuous rock mass. In most cases, the environment includes varying mining depths, mine spans, and layouts as well as different rock types and geological structures. At the same time, the vast areal extent of the typical ‘tabular’ orebodies in South Africa suggests highly variable rock mass and structural properties across the mining tenure. The updated version of the code will require substantial calibration to test the proposed design criterion against actual recorded rock mass responses. This is expected to be a complex process due to the vast number of variables that should be accounted for. Calibration of numerical codes to actual rock mass response should, in theory, consider the impact of these potential conditions or environments. However, numerical modelling must apply a process of eliminating unnecessary details. The selection of the critical factors that must be included should follow a scientific approach or process. It is suggested that the code calibration should be an iterative process through which the code's sensitivity to specific input parameters and conditions is tested against the selected rock mass responses. To start the planned calibration process, the behaviour of the TEXAN code based on certain input parameters was evaluated as a sensitivity study. The results include the identification of parameters/conditions that are ‘critical’ to future calibration of this code by ensuring that the following is clear:

  1. the importance of establishing accurate values (or ranges of values) to some parameters and

  2. which parameters/conditions need to be included in the models.


In the physical world, there are often a vast number of factors that may influence the outcomes of a specific situation or act. At its simplest, each of these factors may impact significantly, moderately, or have no noticeable impact on the situation or act. It is often the case that only the factors that can be shown to have a considerable impact are considered ‘critical’ and are applied in evaluating the possible outcomes of a situation or act. Frequently, also, no real process is applied in selecting these critical factors, or the values allocated to them, but a subjective selection is made based on what is thought to be important.

This content is only available via PDF.
You can access this article if you purchase or spend a download.