Effect of Rock Properties on Electromagnetic Radiation Characteristics Generated by Rock Fracture During Uniaxial Compression

Wei, Menghan; Song, Dazhao; He, Xiaocong; Li, Zhenlei; Qiu, Liming; Lou, Quan

doi:10.1007/s00603-020-02216-x

Cited by 36 publications

(16 citation statements)

References 37 publications

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“…At present, there are mainly theories about the mechanism of EMR signal generation in coal and rock, such as crack propagation effect [29], piezoelectric effect [30,31], friction effect [32], electrodynamics effect [33], and thermionic emission effect [34]. rough the analysis of the crack propagation mode and mechanical properties of coal samples with different α, we believe that the crack propagation effect is the main factor affecting the difference of the EMR signal of samples with different α. e propagation mode of cracks leads to the difference of free charge generation and separation, which leads to the difference of EMR signal characteristics.…”

Section: Time-frequency Response Mechanism Of Emr Signals With Different αmentioning

confidence: 99%

“…Cracks propagate unstably under load, and positive and negative charges are generated and accumulated on the crack wall. With the opening and closing of the crack and the vibration of the crack wall, the positive and negative charges continue to separate and radiate energy in the form of electromagnetic waves, which results in EMR [34,35]. As shown in Figures 11 and 12, the failure of samples with different α has different crack propagation modes and causes different EMR signal generation mechanisms.…”

Section: Time-frequency Response Mechanism Of Emr Signals With Different αmentioning

confidence: 99%

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Time‐Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles

Song

Yin

et al. 2021

Shock and Vibration

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It is vital to understand the electromagnetic radiation’s time-frequency characteristics in the process of coal and rock failure with different joint angles in order to reveal the generation mechanism of the electromagnetic radiation (EMR) and improve the accuracy of EMR early warning. We studied the time-frequency characteristics of EMR signals of coal samples with different joint angles. The study finds that, (1) with the increase of joint angle, the failure time and peak load of samples decrease first and increase later, and the postpeak failure time decreases gradually. The EMR counts’ peak value showed a slow rise, a sharp rise, and a slow rise in the three intervals of α = 0° to 45°, 45° to 60°, and 60° to 90°, respectively. The accumulated EMR counts showed a steady upward trend. The duration of the EMR waveform, the dominant frequency of the EMR, and the peak number of the frequency spectrum of coal samples are on the rise. (2) As the joint angle increases, the samples’ failure mode changes from the stage fracture dominated by tension cracks to the rapid fracture with the coexistence of shear and tension cracks and finally to the burst fracture which produces a large number of fragments. This is also the main reason for the difference of the EMR generation mechanism and the signal of samples with different joint angles. (3) According to the experimental results, we established the modified formulas for calculating the EMR threshold value and deviation of coal and rock with joints under different stress environments and revealed that the longer the EMR waveform duration, the higher the dominant frequency, and the more the number of spectrum peaks, the greater the burst risk of coal and rock.

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Section: Time-frequency Response Mechanism Of Emr Signals With Different αmentioning

confidence: 99%

Section: Time-frequency Response Mechanism Of Emr Signals With Different αmentioning

confidence: 99%

Time‐Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles

Song

Yin

et al. 2021

Shock and Vibration

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“…They have discussed the relationship between the EMR intensity with respect to elastic modulus, compressive strength and quartz content of the rocks. Through their analysis they found that the quartz content is not a decisive factor for the EMR signals, but these signals are more dependent on the complex stress-induced cracks and their propagation [135].…”

Section: Friedemann Freund From Nasa Ames Researchmentioning

confidence: 99%

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

2020

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Development of the deformation monitoring techniques for the infrastructures so as to avoid catastrophic failure and resulting economic/human loss has remained a key interest of scientists and engineers. Among various deformation monitoring techniques utilized and explored by groups of researchers, electromagnetic radiation detection is one of the intriguing techniques which has remained popular in researchers’ community till today. Almost every type of material is being explored and studied by researchers for the electromagnetic emissions when subjected to external loading and/or failure. Experimental and theoretical investigations are demonstrating these emissions to be a suitable candidate for the deformation monitoring, as a failure predictor and to know about the complex phenomenon of fracture. This article presents extensive literature review and a rigorous discussion on the work done in the past several decades regarding the exploration of electromagnetic emissions from a wide variety of materials and the underlying physical mechanisms. Thus, this review is an attempt to highlight main findings, proposed physical mechanisms, prospective applications, future scope and challenges of the electromagnetic emission detection technique.

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“…For example, Kurlenya et al 46 analyzed the frequency characteristics of EMR in the fracture process of rock and proposed the S‐shaped curve of dominant frequency distribution of EMR corresponding to deformation and failure process of rock. Wei et al 47 confirmed that with the continuous evolution of cracks, the main frequency of EMR shifted from high‐frequency to low‐frequency through uniaxial compression on different types of rock materials. Bahat et al 48 observed the fracture characteristics of chalk with a microscope through uniaxial and triaxial rock mechanics test, and compared the fracture process with the frequency of EMR, and found that the larger the crack expansion, the lower the frequency of EMR and the higher the intensity of EMR.…”

Section: Introductionmentioning

confidence: 95%

“…Some researchers studied the failure characteristics of coal and rock materials with different properties under uniaxial compression, analyzed the relationship between EMR and characteristic parameters of coal and rock, and studied the change law of amplitude and main frequency at different loading stages. 15,47,[56][57][58][59] These researches mainly investigated the influences of mechanical properties and electrical properties of materials, loading condition and environmental condition, on the EMR waveform, amplitude, and frequency during rock fracturing. However, the investigation of the effect of composition and structure of coal and rock, especially cracks, pores, defects, and weak structural surfaces, on EMR has received less attention in the literatures.…”

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confidence: 99%

Experimental investigation on time‐frequency evolution characteristics of electromagnetic radiation below ULF reflecting the damage performance of coal or rock materials

Yang

Rui

et al. 2021

Structural Contr & Hlth

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As a form of energy dissipation, electromagnetic radiation (EMR) is gradually becoming a mainstream method prediction method for damage monitoring of coal and rock. To better improve the prediction accuracy of EMR, it is crucial to investigate time-frequency characteristics of EMR and the influence of coal and rock properties on EMR that occurs in the fracture process. In this paper, the deformation and fracture process of raw coal, shaped coal, and cement specimens under compression are observed, and time-frequency evolution characteristics of EMR below ultralow frequency (ULF) under different loading stages are evaluated. Then, the inherent reasons of time-frequency evolution of EMR reflecting the damage performance are analyzed. Meanwhile, the effect of loading condition and composition and structure of materials on EMR is discussed. Results show that there is obvious EMR below ULF in the deformation and fracture process of coal and rock materials, and the combined denoising method of ensemble empirical mode decomposition (EEMD) and wavelet is suitable for extraction of EMR. Besides, the amplitude is approximately inversely proportional to frequency of electromagnetic signals, and the relationship between pulse count of EMR and damage is related to the homogeneity of coal and rock materials. Moreover, the time-frequency characteristic parameter of EMR, such as amplitude, pulse count, and frequency spectrum, can indirectly reflect the damage evolution process of coal and rock. These results can provide a theoretical basis for remote monitoring of coal and rock dynamic disaster using EMR below ULF.coal and rock materials, damage evolution j EEMD, electromagnetic radiation, timefrequency characteristics | INTRODUCTIONThe safe development of the coal industry is crucial to the economic lifeline and energy security of the country, especially in coal-dependent countries such as China, India, and South Africa. With the increasing mining depth, high

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Effect of Rock Properties on Electromagnetic Radiation Characteristics Generated by Rock Fracture During Uniaxial Compression

Cited by 36 publications

References 37 publications

Time‐Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles

Time‐Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles

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

Experimental investigation on time‐frequency evolution characteristics of electromagnetic radiation below ULF reflecting the damage performance of coal or rock materials

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