Extending empirical evidence through numerical modelling in rock engineering design
GS Esterhuizen
Models are used in engineering to reproduce reality as faithfully as possible
so that the expected response of a system for given actions or inputs can be
determined. In the field of rock engineering, both empirically based and
numerical models are widely used to determine the likely response of the
rock surrounding excavations. Many of the empirical models are developed
from statistical analysis of case histories or from direct observation;
however, empirical models are limited because they should be used only
within the range of conditions of the observational database. Synergy
exists between empirical and numerical models, because empirical models
can be used to calibrate and validate numerical models. The empirical
approach can benefit from the capability of numerical models to investigate
specific mechanisms, which would not be possible using observations
alone. Two cases are presented in which the synergy between empirical and
numerical models is demonstrated. The first case examines the analysis of
discontinuity effects on the strength of slender pillars in limestone mines,
and the second case evaluates the effects of stress orientation on coal mine
entry stability. It is concluded that numerical model calibration and verification
comprises an important first stage in the successful application of
models in rock engineering design. Application of numerical models allows
mechanisms and interactions of various parameters to be analysed, greatly
improving the understanding of the system. The improved understanding
can be used to extend the application of empirical design methods,
resulting in improved safety and efficiency of rock engineering designs.
Keywords: rock engineering, empirical design, numerical modelling.