Prediction of Porosity and Permeability of Caved Zone in Longwall Gobs |
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Authors: | C Özgen Karacan |
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Institution: | (1) Department of Physics, Wright State University, Dayton, OH 45435, USA |
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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. |
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Keywords: | |
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