Study On Characteristics And Mechanism Of Electromagnetic Radiation Response To Physical And Mechanical Properties Of Coal Or Rock

Through the test of physical and mechanical properties and electromagnetic radiation (EMR) of coal or rock specimens under uniaxial compression, the author studied deeply and systematically on the EMR response characteristics and regularities of coal or rock with different physical and mechanical properties such as the lithology, component, structure, homogeneous degree and the intensity and so on. Results show that the rules and distribution characteristics of EMR signal are different during the fracture process of different lithology coal or rock; the impact of components of coal or rock on intensity and frequency of EMR is remarkable; when the homogeneous degree or strength of specimens is high the change is stable and the increasing tendency of EMR is more remarkable; in microscopy, the microstructure of impact coal specimens shows brittle characteristics, the EMR signal is more centralized; and the microstructure of outburst coal not only shows brittle characteristics but also shows plastic characteristics, the EMR signal of which shows a slowly increasing tendency. Further more, the resistance of coal or rock has important effect on generation and propagation of EMR.The author experimentally studied the EMR characteristics of pre-cracked rock specimens, then simulated the fracture process of pre-cracked rock specimens with RFPA2D software and computed the EMR signal based on the statistical damage theory and stress-electric coupling model. Results indicate that as the crack obliquity increases, the main deformation form changes from shear deformation to tension-shear composite deformation gradually. Meanwhile, the EMR impulse signal becomes much more abundant. The results establish a theory basis for the study of fracture EMR characteristics of coal seam containing soft stratification in field.Based on the feature information extraction technology of time series signal, the author studied the characteristics and statistic rules of the EMR kurtosis, the precursory mutation coefficient and the Hurst index, and made a regression analysis of the correlation between the EMR and physical and mechanical properties of coal or rock. The EMR feature information can represent the mechanical property of coal or rock and the information of fracture process and the acuity degree of deformation.The author studied the mechanical mechanism of tensile fracture and shear fracture, and the corresponding EMR generation mechanism. And revealed the EMR response mechanisms of deformation and fracture of impact tendency coal and outburst tendency coal and pre-cracked specimens. The influence mechanism of the quartz content, pre-crack, litholoy and the intensity on EMR was also theoretically analyzed and studied. And based on wave theory and fracture mechanics theory, the quantitative correlation between EMR frequency and physical property parameters of coal or rock in crack propagation was established.The attenuation law of EMR propagation impacted by excavation underground was studied preliminarily. The results indicate that there is a close relationship between EMR attenuation and stress distribution in coal seam.In this paper, the author studied the EMR response characteristics and mechanisms of different physical mechanical properties of coal or rock systematically, and established the relationship between EMR and physical mechanical properties of coal or rock. There is great theoretical and practical significance on further revealing the mechanism of deformation and fracture of coal or rock and mechanism of different dynamic disasters, evaluating the stress state of coal or rock and forecasting dynamic disasters with EMR more accurately.