A study on fractal characteristics of acoustic emission under multiple heating and loading damage conditions

Kong, Biao; Zhuang, Zedong; Zhang, Xiaoxin; She, Jia; Lü, Wei; Zhang, Xiangyang; Zhang, Wenrui

doi:10.1016/j.jappgeo.2022.104532

Cited by 6 publications

(4 citation statements)

References 27 publications

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“…The analysis of the acoustic emission characteristics can obtain the evolution law of coal damage and crack extension. ,− The emission signals recorded in the indoor test were processed to obtain the acoustic emission ringing count rate at different loading moments. Figure shows the evolution of the acoustic emission ringing count rate at different loading moments.…”

Section: Resultsmentioning

confidence: 99%

Damage Evolution Characteristics and Constitutive Model for Coal and Rock under Asymmetric Loading

Wang,

Zhao,

Zhang

et al. 2024

ACS Omega

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Tunnels and shaft mining roadways are often subjected to varying degrees of asymmetric loading due to terrain relief or project excavation. In order to analyze the influence of the asymmetric degree of loading on the mechanical properties and damage rupture law of coal rock, uniaxial compression tests of coal rock under four asymmetric loading modes were carried out, the influence of the asymmetric coefficients of loading on macro- and micromechanical properties of coal and rock was analyzed, and a statistical damage constitutive model of coal and rock was established to reflect the asymmetric loading degree. The results of the study show that the peak stress of the coal rock decreases gradually with the increase in the asymmetric coefficient of loading, and the two are linear functions of each other. The distribution of the acoustic emission ringing count peak value is concentrated under uniform loading, while the acoustic emission ringing count rate presents a multipeak phenomenon under asymmetric loading, and the peak value points are scattered. In the case of asymmetric loading, the stress concentration on the edge of the upper loading plate leads to shear failure, and the microscopic cracks are concentrated near the interface between the loading zone and the nonloading zone. According to the established damage constitutive model, when the damage degree is the same, the larger the asymmetric coefficient, the smaller the strain value, which indicates that the asymmetric loading promotes the damage of coal and rock.

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Section: Resultsmentioning

confidence: 99%

Damage Evolution Characteristics and Constitutive Model for Coal and Rock under Asymmetric Loading

Wang,

Zhao,

Zhang

et al. 2024

ACS Omega

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“…AE signal is active especially when the crack width expands under 300–500 °C. It has been also reported that AE signals increase with heating under the loading condition compared to without heating 27 .…”

Section: Introductionmentioning

confidence: 89%

Monitoring the gasification area and its behavior in underground coal gasification by acoustic emission technique instead of temperature measurement

Hamanaka

Ishii

Itakura

et al. 2023

Sci Rep

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Underground Coal Gasification (UCG) requires monitoring of the gasification area because the gasification process is invisible and the reaction temperature exceeds 1000 °C. Many fracturing events that occurred due to coal heating can be captured with Acoustic Emission (AE) monitoring technique during UCG. However, the temperature conditions to generate fracturing events during UCG have not yet been clarified. Therefore, the coal heating experiment and small-scale UCG experiment are conducted by measuring the temperature and AE activities in this research to examine the applicability of the AE technique instead of temperature measurement as a monitoring method during UCG. As a result, many fracturing events are generated when the temperature of coal is changed drastically, especially during coal gasification. Besides, AE events increase in the sensor near the heat source and AE sources are expanded widely with the expansion of the high-temperature region. AE monitoring is an effective technique for the estimation of the gasification area during UCG instead of temperature monitoring.

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“…Based on this, the experimental process in Figures 2 and 3 is divided according to the temperature stages, and the change law of the AE signal is analyzed. The third stage of the sample has entered the high-temperature state after rapid warming, and the subsequent warming is slower [10]. Figure 2 shows the law of the change of AE counts with time during the heating process of coal.…”

Section: Ae Counting and Energy Analysis During Spontaneous Combustio...mentioning

confidence: 99%

“…Han et al investigated the AE characteristics of different coal samples during the process under uniaxial compression and found that there were significant differences in the AE characteristics of coal with different strengths during the compression process [9]. Kong et al [10][11][12] studied the AE nonlinear and fractal characteristics of AE under multiple heating and loading damage conditions of coal rocks. Chen, under laboratory conditions, analyzed the acoustic emission count, dissipation energy, and fracturing point distribution of different deformation stages of coal [13].…”

Section: Introductionmentioning

confidence: 99%

Study on the Variation Laws and Fractal Characteristics of Acoustic Emission during Coal Spontaneous Combustion

et al. 2023

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Acoustic emission (AE) technology has the advantage of online localization to study the change laws of AE in the process of coal spontaneous combustion and to reveal the generation mechanisms of AE signal during the process of heating and rupture of coal body from a microscopic perspective. This paper first constructs a large-scale coal spontaneous combustion AE test system and conducts experimental tests on the AE signal in the process of coal spontaneous combustion. The results show that with the increase of temperature in the process of coal spontaneous combustion, the AE signal shows a trend of increasing fluctuations. Low-temperature nitrogen adsorption experiments studied the pore structure of coal spontaneous combustion, and the results showed a correspondence between the development of pores and the temperature of coal spontaneous combustion. Further, through the analysis of the evolution of the pore structure of coal through Fourier transform and fractal theory, it is found that the high-frequency main frequency AE signal and average frequency are continuously enhanced with the increase of temperature. The fractal dimension of the pore structure and the fractal dimension of the AE count of the coal body first rise and then decline. The mechanism of coal spontaneous combustion AE of coal is revealed, and the pore development caused by thermal stress when coal heats up is the main source of AE signal generation. The research in this paper is of great significance for applying AE technology to detect the position of coal spontaneous combustion.

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A study on fractal characteristics of acoustic emission under multiple heating and loading damage conditions

Cited by 6 publications

References 27 publications

Damage Evolution Characteristics and Constitutive Model for Coal and Rock under Asymmetric Loading

Damage Evolution Characteristics and Constitutive Model for Coal and Rock under Asymmetric Loading

Monitoring the gasification area and its behavior in underground coal gasification by acoustic emission technique instead of temperature measurement

Study on the Variation Laws and Fractal Characteristics of Acoustic Emission during Coal Spontaneous Combustion

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