Time-Varying Multifractal Characteristics and Formation Mechanism of Loaded Coal Electromagnetic Radiation

Dynamic collapses of deeply mined coal rocks are severe threats to miners. To predict the collapses more accurately using electromagnetic radiation (EMR), we investigate the time-varying multifractal characteristics and formation mechanism of EMR induced by underground coal mining. A series of uniax...

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Bibliographic Details
Published in:Rock mechanics and rock engineering 2014-09, Vol.47 (5), p.1821-1838
Main Authors: Hu, Shaobin, Wang, Enyuan, Li, Zhonghui, Shen, Rongxi, Liu, Jie
Format: Article
Language:English
Subjects:
Applied sciences
Buildings. Public works
Civil Engineering
Coal
Coal mining
Damage
Dissipation
Earth and Environmental Science
Earth Sciences
Electromagnetic radiation
Electromagnetics
Evolution
Exact sciences and technology
Fractal analysis
Fractals
Fracture mechanics
Geophysics/Geodesy
Geotechnics
Mathematical models
Original Paper
Radiation
Rock mechanics
Rocks
Soil mechanics. Rocks mechanics
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Summary:Dynamic collapses of deeply mined coal rocks are severe threats to miners. To predict the collapses more accurately using electromagnetic radiation (EMR), we investigate the time-varying multifractal characteristics and formation mechanism of EMR induced by underground coal mining. A series of uniaxial compression and multi-stage loading experiments with coal samples of different mechanical properties were carried out. The EMR signals during their damage evolution were monitored in real-time; the inherent law of EMR time series was analyzed by fractal theory. The results show that the time-varying multifractal characteristics of EMR are determined by damage evolutions process, the dissipated energy caused by damage evolutions such as crack propagation, fractal sliding and shearing can be regard as the fingerprint of various EMR micro-mechanics. Based on the Irreversible thermodynamics and damage mechanics, we introduced the damage internal variable, constructed the dissipative potential function and established the coupled model of the EMR and the dissipative energy, which revealed the nature of dynamic nonlinear characteristics of EMR. Dynamic multifractal spectrum is the objective response of EMR signals, thus it can be used to evaluate the coal deformation and fracture process.
ISSN:0723-2632
1434-453X
DOI:10.1007/s00603-013-0501-9