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Prediction of porosity and permeability of caved zone in longwall gobs.

Authors
Karacan-C÷
Source
Transp Porous Media 2010 Mar; 82(2):413-439
NIOSHTIC No.
20036544
Abstract
The porosity and permeability of the caved zone (gob) in a longwall operation impact many ventilation and methane control related issues, such as air leakage into the gob, the onset of spontaneous combustion, methane and air flow patterns in the gob, and the interaction of gob gas ventholes with the mining environment. Despite its importance, the gob is typically inaccessible for performing direct measurements of porosity and permeability. Thus, there has always been debate on the likely values of porosity and permeability of the caved zone and how these values can be predicted. This study demonstrates a predictive approach that combines fractal scaling in porous medium with principles of fluid flow. The approach allows the calculation of porosity and permeability from the size distribution of broken rock material in the gob, which can be determined from image analyzes of gob material using the theories on a completely fragmented porous medium. The virtual fragmented fractal porous medium so generated is exposed to various uniaxial stresses to simulate gob compaction and porosity and permeability changes during this process. The results suggest that the gob porosity and permeability values can be predicted by this approach and the presented models are capable to produce values close to values documented by other researchers.
Keywords
Combustible-gases; Exposure-assessment; Exposure-levels; Exposure-methods; Gas-filters; Injury-prevention; Longwall-mining; Measurement-equipment; Mining-equipment; Mining-industry; Porous-materials; Underground-mining; Ventilation; Ventilation-systems; Author Keywords: Fractals; Fractal permeability; Longwall gobs; Caved zone; Porous media; Hagen-Poiseuille flow; Fragmentation
Contact
C. ÷zgen Karacan, NIOSH, Pittsburgh Research Laboratory, Pittsburgh, PA 15236
CODEN
TPMEEI
Publication Date
20100228
Document Type
Journal Article
Email Address
cok6@cdc.gov
Fiscal Year
2010
NTIS Accession No.
NTIS Price
Issue of Publication
2
ISSN
0169-3913
NIOSH Division
OMSHR
Priority Area
Mining
Source Name
Transport in Porous Media
State
PA
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