Research on Acoustic Emission and Electromagnetic Emission Characteristics of Rock Fragmentation at Different Loading Rates

Abstract

The relationships among the generation of acoustic emission, electromagnetic emission, and the fracture stress of rock grain are investigated, which are based on the mechanism of acoustic emission and electromagnetic emission produced in the process of indenting rock. Based on the relationships, the influence of loading rate on the characteristics of acoustic emission and electromagnetic emission of rock fragmentation is further discussed. Experiment on rock braking was carried out with three loading rates of 0.001 mm/s, 0.01 mm/s, and 0.1 mm/s. The results show that the phenomenon of acoustic emission and electromagnetic emission is produced during the process of loading and breaking rock. The wave forms of the two signals and the curve of the cutter indenting load show jumping characteristics. Both curves have good agreement with each other. With the increase of loading rate, the acoustic emission and electromagnetic emission signals are enhanced. Through analysis, it is found that the peak count rate, the energy rate of acoustic emission, the peak intensity, the number of pulses of the electromagnetic emission, and the loading rate have a positive correlation with each other. The experimental results agree with the theoretical analysis. The proposed studies can lead to an in-depth understanding of the rock fragmentation mechanism and help to prevent rock dynamic disasters.

A review on deformation-induced electromagnetic radiation detection: history and current status of the technique

“…They have related the resulting EMR signals with the temperature [106]. Similarly, some other research groups have studied EMR detection from rocks having prefabricated cracks [107] and from rocks failing at different loading rates [108]. Liu and Wang have tested rock samples extracted from a copper mine.…”

Simulation and Experimental Study on the Discontinuous Dynamic Impact on Unidirectional Confined Coal-Rock Damage

“…e microscopic damage characteristics of rock materials are mainly represented by acousto-optic electromagnetic signals, which can reflect the evolution process of internal damage of rock materials [16]. At present, the research methods of rock material damage characteristics include the following categories: the statistics of rock damage quantity based on ultrasonic detection technology; the rock damage research based on nuclear magnetic resonance technology [17,18]; rock damage positioning research based on acoustic emission [19][20][21]; evolution study of rock temperature field based on infrared thermal imaging technology [22,23]; simulation of rock damage under impact load based on ANSYS/LS-DYNA or other numerical software [24,25]; and research on digital speckle techniques for rock failure and 6…”

Physical Fields as Derivative of Deformation of Rock Massif and Technology of Their Monitoring

“…The physical and chemical bases of intermolecular links of rocks are at the same time precursors of the occurring disturbances of these links, the cause of which is an increase in stresses in the rocks and subsequent elastic or residual deformations. On the assumption of the basics of intermolecular links, it is obvious that electromagnetic fields are an indicator, since crystal lattice deformations cause a change in the distances between atoms and quantummechanical fluctuations of the electron density of particles (molecules, atoms) [12][13][14][15][16][17][18][19][20][21][22][23][24]. The instantaneous distribution of the electric charge of the molecule, which corresponds to the instantaneous dipole moment of the molecule (or a higher order multipole moment), induces an electric multipole moment in another molecule.…”