ABSTRACT: A review of published literature reveals case histories whereby the entire periphery of a coal pillar has “burst” out as a single event during first workings, the associated energy and material release causing significant damage to adjacent roadways and any equipment/infrastructure located within said roadways. Such events are distinct from coal burst events during first workings such as that at the Austar Mine in 2014, or those linked to overburden bumps related to either horizontal stress-driven slip along major faults and/or thick, massive strata units in the overburden or floor of the coal seam. The paper considers as to how the necessary “unstable” conditions for a pillar burst event could conceivably be generated, based on established coal pillar mechanics, specific pillar loading conditions and the shear-restraint of horizontal planes according to both cohesion and friction. The associated hypothesis is applied to a published example to test its veracity.
The longer-term objective of this type of back-analysis is to provide a “cause and effect” list of geological, geotechnical and mine layout circumstances that can and indeed have resulted in entire coal pillar bursts during underground coal mining activities, being able to predict the likely propensity for such events prior to mining being a mandatory requirement in an effective prevention or consequence mitigation process.