Brown, I.R. 1981 Design of panel pillars, Huntly East mine. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 360 21 p.
Abstract: Room and pillar partial extraction in the Kupakupa seam is planned at Huntly East mine. A semi-empirical approach has been used to establish suitable pillar sizes in this part of the mine. Data from the adjacent Taupiri Extended Mine, worked over sixty years ago, was used to infer the strength of 1m blocks of coal. Pillar loads have been calculated using tributary area theory, and pillar strength calculated from a statistically derived strength-size relationship. Graphs are used to show the factor of safety versus pillar width at various depths. When the room height is 3.5m, 17m wide pillars at 110m depth have a factor of safety of 1.6. A lower factor of safety, and hence smaller pillar size, should only be considered if a monitoring programme and further rock mechanics work is undertaken.