Basic Study On Microwave Radiation Rules And Its Mechanism Of Loading Coal In Deformation And Fracture Process

In this paper, using laboratory experiments and theoretical analysis, microwave radiation rules and mechanism of thermal radiation of loading coal in deformation and fracture process is studied and basic theoretical is analyzed on how to apply the method to predict the coal or rock dynamic disaster.Firstly, the experiment system of microwave radiation effect of coal in natural condition, heated coal in cooling process, and loading coal under different loading methods (such as uniaxial compression and tensile test.) is originally established. Accordingly, the experiment scheme is established too. The effect and rules of microwave radiation of coal is originally studied and the three experimental phenomena are explained scientifically and rationally.Secondly, through analyzing to the experimental data of microwave radiation of coal specimens, the varying pattern in cooling process and in deformation and fracture process of coal, are studied. The influence of different factors on microwave radiation of loading coal is analyzed. Having analyzed the stress-strain curve of coal, the corresponding change of brightness temperature curve is obtained and therefore sensitive section and dullness section in brightness temperature curve is originally divised, which provides a theoretical basis of predicting the coal or rock dynamic disaster.Thirdly, the mechanism of micro-generation mechanism of electromagnetic radiation and the relationship between electromagnetic radiation and thermal radiation is discussed.Based on physical foundation of fracture by using scanning electron microscopy (SEM) character of the Griffith frature in coal is analized. With macro-fracture mechanics theory, the macro-fracturing of coal is the result of nucleation and growth phenomenon of micro-fracture. Based on the energy theory, fracture criteria of crack in the semi-static circumstances is derived. And on the micro-fracture mechanics, quoting crack tip atoms particle radiation cleavage and dislocation atomic model, according to the nonlinear thermo-mechanical theory, the generation mechanism of fracture particles thermal radiation is derived. Thermo-mechanical coupling effect of loading coal in deformation and fracture process is analyzed.Based on the statistical damage theory and thermo-mechanical coupling theory, the constitutive equation of statistics damage of coal strength and more extensive statistical coupling model of statistics damage and thermo-mechanical are obtained. Finally, according to electromagnetic field and electromagnetic wave theory, the propagation mechanism of microwave in the lossy media is studied. Based on Maxwell's equations the attenuation equation of microwave propagation in lossy media is obtained with Eview software. With the electric dipole model the relationship between the radiation power and frequency is discussed. Summing up the experiences of the predecessors, the influence factors of the electric parameters of coal or rock is discussed. Then the propagation characteristics of the electromagnetic wave in the interface of different media is studied. The interaction between the microwave and gas molecules is analyzing. Through the above analysis, the microwave radiation method is a promising and early-warning technology of coal or rock dynamic disaster worth of further study .