ABSTRACT
Coal pillar structures are represented with various aspects of strata mechanics, from laboratory stability investigations to design implication. Areas of interest are: Mini pillars investigations examine the applicability of coal as a prototype model material. The coal pillar models show the possibility of the solving a certain number of problems relating to pillar deformation and failure. Time dependent deformation of coal pillars is an important parameter of mine stability. Strength of coal pillar representations utilize knowledge from many fields and suggests a need for adequate pillar design formulas for various coal types with different properties and behaviour. Protective pillars are discussed with the solid coal or which is partially recovered. Final comments are made in regard to shaft mining. Since the end of the last century, a number of investigators have studied the relationship between compressive strength and sample size.
