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INFLUENCE OF FRACTURING ON STATIC COAL ELECTRIC
CONDUCTIVITY L.I. Stefanovich1*, E.P. Feldman1, О.V. Chesnokova1 1Institute for Physics of Mining Processes the
National Academy Sciences of Ukraine, Dnipro, Ukraine 1*Corresponding author: e-mail: listef2591@ukr.net Physical and
technical problems of mining production, 2019, (21), 43-54. https://doi.org/10.37101/ftpgp21.01.003 ABSTRACT Purpose.
To analyze how coal fracturing affects its direct current conductivity at
various crack concentrations and at different ratios between crack sizes and
sample ones. Methods.
The work is based on using the analogy between
electric current and fluid motion in potential flow around solids. To find
analytical dependencies, asymptotic research methods are used. To check the
analytical laws, a numerical analysis of the obtained integral expressions is performed. Findings. It was found that when an electric current
passes through a cracked coal sample in the form of a plate, additional
resistance to direct current arises. It is due to the fact
that the presence of cracks not only reduces the area of the conductive
channels, but also lengthens the path of current flow due to an increase in
the tortuosity of the conductive channels. The functional dependences of the
emerging additional resistance of coal on its cracking coefficient are obtained. As a result of numerical
analysis, the curves of the dependence of the additional resistance on the
fracture coefficient are obtained. For small sample sizes, they are
essentially nonlinear. For large sample sizes, the dependence of the
additional resistance on the fracture coefficient is linear. Originality. Using
the analogy between electric current and fluid motion during potential flow
around solids, new functional dependences of the additional resistance of
coal caused by cracks are obtained, depending on the
fracturing coefficient for various ratios of the sizes of the coal sample and
the sizes of cracks. Practical implications. The
analytical dependences of the electrical resistance on the fracture coefficient obtained in
this work can be used in an experimental study of
coal cracking by impedance
spectroscopy. A preliminary study of the nature of fracturing of fossil coal
by methods of measuring its electrical conductivity allows us to predict how
quickly the outburst will develop during mining of a coal seam. Keywords:
electrical conductivity of coals, system of cracks, fracturing coefficient,
hydrodynamic analogy, relative additional resistance. REFERENCES 1.
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