Effect of Rock Properties on Electromagnetic Radiation Characteristics Generated by Rock Fracture During Uniaxial Compre
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ORIGINAL PAPER
Effect of Rock Properties on Electromagnetic Radiation Characteristics Generated by Rock Fracture During Uniaxial Compression Menghan Wei1,2 · Dazhao Song1,2 · Xueqiu He1,2,3 · Zhenlei Li1,2 · Liming Qiu1,2 · Quan Lou4 Received: 2 December 2019 / Accepted: 24 July 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The phenomenon of electromagnetic radiation (EMR) generated by rock fracture is relatively common. Due to different properties of rock, the variation laws and distribution characteristics of signals in time and frequency domain are significantly different. In this paper, the uniaxial compression experiments of four different kinds of rocks were carried out under the same loading conditions. EMR response characteristics during loading were studied, and the relationship between EMR signal statistics and mechanical parameters or quartz contents of rocks were analyzed. However, quartz content is not a decisive factor since quartz-free rock can also produce significant EMR signals when it fractures. Quartz content does not stimulate the activity and intensity of EMR signals generated by rock fracture. For the same kind of rock, specimen with larger elastic modulus tend to exhibit higher EMR signal intensity. Activity of EMR signals is not strictly proportional to the compressive strength of rocks but affected by complex stress-induced crack events during the loading process. With the continuous evolution of cracks, the dominant frequency of EMR signal shifts from a higher band to a lower frequency. As the quartz content decreases, the dominant frequency of EMR signal appears in a higher frequency band. Keywords Electromagnetic radiation · Fracture · Rock properties · Quartz content List of Symbols A Signal amplitude S Crack area t Time l Crack length CR Rayleigh wave speed W Sample width E Elastic modulus 𝜌 Density 𝜈 Poisson’s ratio σs Yield stress σc Compressive stress * Dazhao Song [email protected] 1
School of Civil and Resources Engineering, University of Science and Technology Beijing, Beijing, China
2
Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine, University of Science and Technology Beijing, Beijing, China
3
Zhong-an Academy of Safety Engineering, Beijing, China
4
School of Municipal and Environmental Engineering, Henan University of Urban Construction, Henan Province, Pingdingshan, China
D Electric polarization d Piezoelectric constant T Stress ε Permittivity U Electric field strength R Strain C Elastic constant V Volume p Dipole moment
1 Introduction It is well known that the fracture of materials is accompanied by the generation of electromagnetic radiation (EMR), which has been widely concerned. So far, crackrelated EMR has been confirmed in laboratory studies of many different materials, such as ice (Fifolt et al. 1993), metal (Jagasivamani and Iyer 1988) and different types of rock (Nitsan 1977; Cress et al. 1987; O’Keefe and Thiel 1995). EMR arising as a result of mechanical loa
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