Abstract:
Practical mining aspects should be considered when conducting pillar designs for bord-and-pillar
layouts. The current methodology for pillar design will result in increasing pillar sizes with depth.
This affects the extraction ratio and will result in onerous ventilation requirements when cutting
large pillars. A holistic approach, including all mining engineering requirements, is required to
ensure that the rock engineering designs are optimized to ensure efficient mining operations and
sustainable production. Bord widths should not only be a function of the rock mass ratings, but
should also be selected to fit the specifications of the mechanized equipment. The use of a ‘squat
pillar’ formula for hard rock is discussed in the paper and the formula based on the exponents of
the Hedley and Grant pillar formula, is explored. The effect of abutments and geological losses on
average pillar stress is also explored. These factors must be considered when designing layouts at
increasing depths.
