Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles
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 th...
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| Format: | Article |
| Language: | English |
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Wiley
2021-01-01
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| Series: | Shock and Vibration |
| Online Access: | http://dx.doi.org/10.1155/2021/8340076 |
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| author | Hongwei Mu Dazhao Song Shan Yin Xueqiu He Liming Qiu Dongfang Su Yang Liu |
| author_facet | Hongwei Mu Dazhao Song Shan Yin Xueqiu He Liming Qiu Dongfang Su Yang Liu |
| author_sort | Hongwei Mu |
| collection | DOAJ |
| description | 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. |
| format | Article |
| id | doaj-art-8e7c18b751b6469dab8cf4e680a463cf |
| institution | Kabale University |
| issn | 1070-9622 1875-9203 |
| language | English |
| publishDate | 2021-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Shock and Vibration |
| spelling | doaj-art-8e7c18b751b6469dab8cf4e680a463cf2025-02-03T06:12:00ZengWileyShock and Vibration1070-96221875-92032021-01-01202110.1155/2021/83400768340076Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint AnglesHongwei Mu0Dazhao Song1Shan Yin2Xueqiu He3Liming Qiu4Dongfang Su5Yang Liu6Department of Safety Engineering, Qingdao University of Technology, Qingdao, ChinaSchool of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaSchool of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaSchool of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaSchool of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaSchool of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaSchool of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, ChinaIt 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.http://dx.doi.org/10.1155/2021/8340076 |
| spellingShingle | Hongwei Mu Dazhao Song Shan Yin Xueqiu He Liming Qiu Dongfang Su Yang Liu Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles Shock and Vibration |
| title | Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles |
| title_full | Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles |
| title_fullStr | Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles |
| title_full_unstemmed | Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles |
| title_short | Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles |
| title_sort | time frequency characteristics and the influence mechanism of the emr from coal with different joint angles |
| url | http://dx.doi.org/10.1155/2021/8340076 |
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