Abstract:
The limit equilibrium model, used in displacement discontinuity codes, is a popular method
to simulate pillar failure. This paper investigates the use of physical modelling to calibrate this
model. For the experiments, an artificial pillar material was prepared and cubes were poured using
the standard 100 mm × 100 mm civil engineering concrete moulds. The friction angle between the
cubes and the platens of the testing machine was varied by using soap and sandpaper. Different
modes of failure were observed depending on the friction angle. Of interest is that significant loadshedding
was recorded for some specimens which visually remained mostly intact. This highlights
the difficulty of classifying pillars as failed or intact in underground stopes where spalling is
observed. The laboratory models enabled a more precise calibration of the limit equilibrium model
compared to previous attempts. Guidelines to assist with calibration of the model are given in the
paper. The limit equilibrium model appears to be a useful approximation of the pillar failure as it
could simulate the stress-strain behaviour of the laboratory models.
