Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Tang, Yang; Okubo, Seisuke; Xu, Jiang; Peng, Shoujian

doi:10.3390/en11051215

Cited by 17 publications

(8 citation statements)

References 28 publications

(37 reference statements)

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Section: Damage Characteristics Of Coal At Different Depthssupporting

confidence: 91%

“…Xue et al [46] analyzed the published results of igneous, metamorphic, and sedimentary rocks and showed that the crack damage stress level (σcd/σc) ranged from 0.73-0.85. In addition, Tang et al [47] found that the initial stress level and damage stress level of coal under triaxial compression were 74.53% and 89.84%, respectively, which are very close to our results. The above analysis shows that there are significant differences in the damage characteristics of coal at different depths, which, to a certain extent, reflects the differences in fracture characteristics of coal seams at different depths.…”

Section: Damage Characteristics Of Coal At Different Depthssupporting

confidence: 91%

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Failure Behavior and Damage Characteristics of Coal at Different Depths under Triaxial Unloading Based on Acoustic Emission

Zhang

Gao

et al. 2020

Energies

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The depth effect of coal mechanical behavior seriously affects the safety and efficiency of deep coal mining. To explore the differences in failure behavior and damage characteristics of coal masses at different depths during the coal mining process, based on the consideration of in situ stress environment, physical properties, and mining disturbance of coal seams, triaxial unloading experiments with acoustic emission (AE) monitoring were conducted on coal samples at four different depths taken from the Pingdingshan coal mine area. The results showed that the AE activity of deep coal was more concentrated, and the cumulative AE energy of coal increased with increasing depth. The cumulative AE energy of the 1050-m coal sample was 69 times that of the 300-m coal sample. The b value representing the microcrack scale decreased with increasing depth, and the rupture degree of deep coal increased. The cracking mode of coal was classified and the failure behavior was analyzed. The cumulative tensile crack percentage of coal increased with increasing depth, and the tensile–shear composite failure occurred in the 300-m coal sample, whereas significant tensile failure occurred in the 1050-m coal sample. In addition, the damage evolution process of coal was divided into three stages, and the characteristic stress of coal was obtained. The ratio of crack initiation stress (σci) to peak stress (σc) increased with increasing depth, and the damage evolution process of deep coal was more rapid. The research results can provide useful guidance for disaster prevention and evaluation of surrounding rock stability during deep coal resource mining in the Pingdingshan coal mine area.

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Section: Damage Characteristics Of Coal At Different Depthssupporting

confidence: 91%

Section: Damage Characteristics Of Coal At Different Depthssupporting

confidence: 91%

Failure Behavior and Damage Characteristics of Coal at Different Depths under Triaxial Unloading Based on Acoustic Emission

Zhang

Gao

et al. 2020

Energies

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“…[1][2][3] AE technology can detect the cracks produced by deformation without delay. 4,5 Nowadays, as an effective monitoring method, AE technology has been widely used in the geotechnical field. 3,[6][7][8] To understand the AE characteristics of rock materials during deformation, researchers conducted many investigations on AE characteristics with different rock or rock-like materials.…”

Section: Introductionmentioning

confidence: 99%

Identification of crack development in granite under triaxial compression based on the acoustic emission signal

Wang

Xue

et al. 2021

International Journal of Distributed Sensor Networks

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To explore the development mechanism of cracks in the process of rock failure, triaxial compression tests with simultaneous acoustic emission monitoring were performed on granite specimens using the MTS rock mechanics test system. The frequency-domain information of the acoustic emission signal was obtained by the fast Fourier transform. The Gutenberg–Richter law was used to calculate the acoustic emission signals and obtain the b-value dynamic curve in the loading process. Combined with the stiffness curve of granite specimens and acoustic emission signal in the time domain and frequency domain, the crack development characteristics in different stages were analyzed. The results showed that the acoustic emission signals of granite samples under triaxial compression can be divided into four stages: quiet period 1, active stage 1, quiet period 2, and active stage 2. b-value attained its maximum value in the active phase 2 when it is close to the sample loss, and then drops rapidly, which means the propagation of cracks and the formation of large cracks. The acoustic emission signal’s dominant frequency was not more than 500 kHz, mostly concentrated in the medium-frequency band (100–200 kHz), which accounted for more than 80%. The proportion of signals in each frequency band can reflect the distribution of the three kinds of cracks, while the change in low-frequency signals can reflect the breakthrough of microcracks and the formation time of macrocracks in granite samples. By fully analyzing the characteristics of acoustic emission signals in the time domain and frequency domain, the time and conditions of producing large cracks can be determined accurately and efficiently.

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“…Hao et al considered unsteady energy release at the postpeak stage and establish a new brittleness index for hard coal [10]. Tang et al obtained the stress thresholds of coal that were in uniaxial and triaxial compression, discussed the energy evolution during the compression, and coupled with the crack volumetric strain [11]. Zhang et al considered the effects of depth on the in situ stress environment and physical properties of coal and conducted triaxial compression experiments on 128 coal samples that were on this basis, showing that, with increasing depth, the elastic energy and dissipated energy increase more rapidly [12].…”

Section: Introductionmentioning

confidence: 99%

Failure Behavior and Energy Storage and Release of Hard Coal under Different Static and Dynamic Loading States

Hao

Pan

et al. 2020

Advances in Civil Engineering

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The study of the energy accumulation and rate of release in hard coal under dynamic, static, and coupled dynamic-static loading and its failure mode is of significance when studying the mechanism underpinning coal mine dynamic disasters such as rock burst, coal, and gas outburst. In this paper, four experimental methods (uniaxial compression, Brazilian splitting, and coupled dynamic-static tensile and coupled dynamic-static compression) were used to analyze the energy accumulation, energy rate of release, and failure modes of this type of hard coal under different loading conditions. It was concluded that (1) the energy accumulation and rate of releases of this type of hard coal under static compression are 17.63–179.90 times and 18.57–13157.89 times those under static tension; the energy accumulation and rate of releases in dynamic compression are 2.11–248.53 and 0.23–48 times those under dynamic tension, respectively. (2) During dynamic loading, the ratio of compressive energy accumulation to tensile energy accumulation is reduced by 1.6 times compared with static loading, and the ratio of compressive energy release to tensile energy rate of release is decreased by 363.84 times compared with static loading. (3) The energy accumulation and rate of releases of this type of hard coal for dynamic tensile are, respectively, 2.64–17.42 and 1.07–5.26 times those under static tensile load; the energy accumulation under dynamic compression is greater than that under static compression, being 0.24–15.04 times that under static compressive, but the energy rate of release under dynamic compression is 0.0003–0.56 times that under static compression. (4) The greater the prepeak energy accumulation, the greater the degree of damage of the coal sample at each stage, and also the higher the degree of fragmentation after the failure. The research results play an important guiding role in further understanding the mechanism of coal mine dynamic disasters.

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Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Cited by 17 publications

References 28 publications

Failure Behavior and Damage Characteristics of Coal at Different Depths under Triaxial Unloading Based on Acoustic Emission

Failure Behavior and Damage Characteristics of Coal at Different Depths under Triaxial Unloading Based on Acoustic Emission

Identification of crack development in granite under triaxial compression based on the acoustic emission signal

Failure Behavior and Energy Storage and Release of Hard Coal under Different Static and Dynamic Loading States

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