Vector characteristics and laws of electromagnetic radiation generated from coal rock fracture
Publication Name
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology
Abstract
The safe mining of coal and other resources is the key to guaranteeing energy security. With the continuous increase in mining intensity and depth, coal and gas outburst and other dynamic disasters pose a serious threat to the safe and efficient mining. As a real-time, non-contact, and highly precursor geophysical monitoring method, electromagnetic radiation (EMR) technology has played an important role in monitoring and warning of coal-rock dynamic disasters. Current research primarily focuses on scalar parameters, overlooking the spatial vector characteristics inherent in the electromagnetic field. Therefore, based on the principle of vector synthesis, the vector characteristics of fracture-induced electromagnetic signals were studied using a self-developed three-axis electromagnetic antenna. Electromagnetic signals on the three axes have obvious differences in the time domain, while the distribution in the frequency domain is relatively consistent. They can be regarded as the components of the e-lectromagnetic field in the three directions. Generated vector field is non-uniformly distributed around the specimen. The directional difference of signals can be used to characterize vectors. There is a clear correlation between the direction of the equivalent vector and the crack surface. The vector electromagnetic field results from combined effects of multiple microcracks. Multi frequency signals can be regarded as the superposition of electromagnetic effects generated by forced and damped oscillations of multiple dipoles in different directions and frequencies. On-site tests show that the use of electromagnetic vector characteristics can assist in identifying fault areas and hazard levels. The research results contribute to further revealing the spatio-temporal evolution of the fracture behavior throughout the entire fracture process. This can lay the foundation for the monitoring and early warning of coal-rock dynamic disasters in a non-contact, spatiotemporal and precise manner.
Open Access Status
This publication is not available as open access
Volume
52
Issue
6
First Page
1096
Last Page
1107