A parametric study on gas outbursts induced by gas desorption

Sheng Zhi, Derek Elsworth

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Violent gas outbursts are one of the most severe hazards in underground mining. When outbursts occur, a large amount of coal and gas is suddenly and violently ejected into the roadway and working area with the possibility of serious hazard and injury. Recent studies have shown that the physical behavior responsible for the energetic failure of coal is entirely consistent with coal viewed as a dual porosity-dual permeability-dual stiffness continuum where strength is proportional to effective stresses, and where effective stresses are controlled by both the pore pressure and varying stress field. Gas desorption driven by overstress is highlighted in this study as the key factor responsible for the increase in pore pressure close to the working face, and implicated together with elevated stress level, permeability evolution and drainage conditions in the triggering of outbursts. In this work, we incorporate the likely mass rates of desorption driven by an increase in abutment stress and mediated by permeability evolution to define the rates and distributions of gas pressure changes. The changing pattern of pressure redistribution is identified, and parametric studies are then performed to investigate all the key factors that influence the redistribution of pore pressure with respect to the deformation of the coal seam. Permeability evolution in the overstressed zone is determined by the evolution of porosity, which is attributed to both the change in effective stresses in the abutment and sorption-induced strain. This model is capable of predicting the potential risk ahead of the working face during mining and can be adapted to different conditions in terms of varying mechanical factors, coal properties and mining methods.

Original languageEnglish (US)
Title of host publication50th US Rock Mechanics / Geomechanics Symposium 2016
PublisherAmerican Rock Mechanics Association (ARMA)
Pages3450-3461
Number of pages12
ISBN (Electronic)9781510828025
StatePublished - Jan 1 2016
Event50th US Rock Mechanics / Geomechanics Symposium 2016 - Houston, United States
Duration: Jun 26 2016Jun 29 2016

Publication series

Name50th US Rock Mechanics / Geomechanics Symposium 2016
Volume4

Other

Other50th US Rock Mechanics / Geomechanics Symposium 2016
CountryUnited States
CityHouston
Period6/26/166/29/16

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

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  • Cite this

    Zhi, S., & Elsworth, D. (2016). A parametric study on gas outbursts induced by gas desorption. In 50th US Rock Mechanics / Geomechanics Symposium 2016 (pp. 3450-3461). (50th US Rock Mechanics / Geomechanics Symposium 2016; Vol. 4). American Rock Mechanics Association (ARMA).