A causation mechanism for coal bursts during roadway development based on the major horizontal stress in coal: Very specific structural geology causing a localised loss of effective coal confinement and Newton’s second law

Abstract

In 2017, one of the international authorities on coal bursts, Mark Christopher, published a paper entitled “Coal bursts that occur during development: A rock mechanics enigma”, in which several relevant technical issues were identified. This paper outlines what is considered to be a credible, first-principles, mechanistic explanation for these three current development coal burst conundrums by reference to early published coal testing work examining the significance of a lack of “constraint” to coal stability and an understanding of how very specific structural geology and other geological features can logically cause this to occur in situ, albeit on a statistically very rare basis. This basic model is examined by reference to published information pertaining to the development coal-burst that occurred at the Austar Coal Mine in New South Wales, Australia, in 2014 and from the Sunnyside District in Utah, the United States. The “cause and effect” model for development of coal bursts presented also offers a meaningful explanation for the statistical improbability for what are nonetheless potentially highly-destructive events, being able to explain the statistical rarity being just as important to the credibility of the model as explaining the local conditions associated with burst events. The model could also form the basis for a robust, risk-based approach utilising a “hierarchy of controls”, to the operational management of the development coal burst threat. Specifically, the use of pre-mining predictions for likely burst-prone and non-burst-prone areas, the use of the mine layout to avoid or at least minimise mining within burst-prone areas if appropriate, and finally the development of an operational Trigger Action Response Plan (TARP) that reduces the likelihood of inadvertent roadway development into a burst-prone area without suitable safety controls already being in place. Keywords: Development coal burst, Wing-cracks, Austar Mine, Sunnyside Mine, Major horizontal stress in coal