Mechanical Properties of Bump‐Prone Coal with Different Porosities and Its Acoustic Emission‐Charge Induction Characteristics under Uniaxial Compression

Ding, Xin; Xiao, Xiaochun; Lv, Xiangfeng; Wu, Di; Xu, Jun

doi:10.1155/2019/7581061

Cited by 5 publications

(8 citation statements)

References 37 publications

(45 reference statements)

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“…The amplitude of intact coal varied continuously during the test, while the amplitude of fractured coal and rock mass changed from disperse to continuity, and the amplitude frequency was high when the stress level was 0.6∼1. The results of this study were consistent with those of Meng et al [38,39]. In the compaction and elastic stages, the amplitude of AE energy was relatively low, and new micro-cracks could not be formed under low stress.…”

Section: Temporal and Spatial Distribution Characteristics Of Acoustic Emission Eventssupporting

confidence: 92%

Research on the Failure Evolution Process of Rock Mass Base on the Acoustic Emission Parameters

et al. 2021

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Fracture mechanics behavior and acoustic emission (AE) characteristics of fractured rock mass are related to underground engineering safety construction, disaster prediction, and early warning. In this study, the failure evolution characteristics of intact and fracture (e.g., single fracture, parallel fractures, cross fractures, and mixed fractures) coal were studied and contrasted with each other on the basis of the distribution of max amplitude of AE. The study revealed some meaningful results, where the value of b (i.e., the distribution characteristic of max amplitude of AE) could represent the failure evolution process of intact and fractured coal. The maximum amplitude distribution of AE events was characterized by Gaussian normal distribution, and the probability of the maximum amplitude of AE events corresponding to 35∼50 dB was the largest. In the stress range of 60∼80%, AE events and maximum amplitude increased rapidly, and the corresponding b value decreased. The energy of AE events showed a downward trend after reaching the maximum value at about 80% stress level. Under the same stress level, the more complex the fracture was, the larger the b value of coal–rock mass was, and the stronger the inhibition effect on the fracture expansion caused by the internal fracture distribution was. Due to the anisotropy of coal–rock mass with a single crack, the distribution of the b value was more discrete, while the anisotropy of coal–rock mass with mixed crack decreased, and the dispersion of the b value decreased. The deformation of cracked coal mainly caused by the adjustment of cracks during the initial loading b value experienced a trend of decreasing first, then increasing, and then decreasing in the loading process. When the load reached 0.8 times of the peak strength, the b value had a secondary decreasing trend, indicating the macroscopic failure of the sample, which could be used as a precursor criterion for the complete failure of coal–rock mass.

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Section: Temporal and Spatial Distribution Characteristics Of Acoustic Emission Eventssupporting

confidence: 92%

Research on the Failure Evolution Process of Rock Mass Base on the Acoustic Emission Parameters

et al. 2021

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“…On the other hand, original pores and fractures affect the coal’s fracture location, and most of the final fracture surface will pass through the initial fracture during coal damage. Overall, the larger the fracture size and higher the development of fractures in the coal, the lower is its compressive strength. , Coal strength is negatively correlated with the logarithm of porosity, and the elastic modulus decreases as the amount of initial damage increases …”

Section: Qualitative Evaluation Of Macroscopic Propertiesmentioning

confidence: 99%

“…Overall, the larger the fracture size and higher the development of fractures in the coal, the lower is its compressive strength. 104,105 Coal strength is negatively correlated with the logarithm of porosity, and the elastic modulus decreases as the amount of initial damage increases. 104…”

Section: Qualitative Evaluation Of Macroscopic Propertiesmentioning

confidence: 99%

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Review on Applications of X-ray Computed Tomography for Coal Characterization: Recent Progress and Perspectives

et al. 2022

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Characterization of microscopic structure and macroscopic physical property are the basis for better understanding of coalbed methane reservoirs. X-ray computed tomography (CT), as an nondestructive measurement, has been widely and successfully applied to characterize the internal structure of coal. In this study, we introduce the principle of CT imaging and the microstructure recognition. A summary of CT imaging-based coal microstructure characterization follows, including three-dimensional (3D) microstructure reconstruction, pore and mineral quantification, and equivalent pore network model construction. We review the methods used to evaluate the macroscopic properties of coal, including porosity calculation, gas adsorption/diffusion rate test, permeability simulation, and mechanical behavior evaluation. This study discusses the application of CT to investigate the evolutionary mechanisms of microstructure and macroscopic properties during gas adsorption, temperature change, and damage deformation. We conclude this review with a summary of the challenges and application perspectives of CT. The small scanning range, limited observation accuracy, functional limitations, lengthy testing process, and high cost are some of the major hurdles in the broad application of CT for coal characterization. In the future, CT should be combined with other techniques to establish full-scale pore and fracture models, identify mineral types in microstructures, and effusively use the advantages of CT by selecting the key points in the evolutionary mechanisms of microstructure and macroscopic properties.

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“…Cylindrical specimens measuring φ 50 mm × 100 mm were prepared, and both ends of each specimen were polished to ensure that the flatness error was less than ±0.02 mm (Figure 1). Affected by the special occurrence state and material composition of coal, as well as the initial damage formed inside, the samples taken from the same block have different characteristics of color uniformity in the macro, which leads to the dispersion of the mechanical properties of coal samples [34,35].…”

Section: Preparation Of Specimensmentioning

confidence: 99%

Analysis of Similarities and Differences between Acoustic Emission and Charge Signal Based on Fractal Characteristics of Coal Fracture

Ding

Xiao

et al. 2020

Advances in Civil Engineering

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Rock burst is a catastrophic dynamic disaster caused by sudden failure and instability of coal, which brings threats to deep coal mining; the AE-charge signals and the fragment distribution are related to both mechanical properties of coal and disaster early warning directly. Hence, the variation of AE and charge induction during coal failure, fractal feature of coal fragments, and their relationship should be studied in depth. In this paper, uniaxial loading test was carried out for coal with bursting tendency samples produced by blocks cored from 800 m depth in Xiaoqing coal mine of the Tiefa Coal Group in northeast China; the fractal characteristics of specimens are obtained by using the statistical fractal method. The mechanics of similarities and differences between acoustic emission and charge signal is investigated by using loading experiments and theoretical analysis. It is found that the fragments of coal have good self-similarity properties; the fractal dimension of the specimens is in the range 2.085–2.521, the maximum range being 2.300–2.468, which is slightly higher than that of rock. The high-amplitude pulses of the acoustic emission and charge are concentrated in the macroscopic fissure development and expansion stage but they have asynchronous characteristics between them. The charge generation process is accompanied by the inhomogeneous deformation and sliding friction; the friction slip is the major one and is analysed theoretically. A theoretical model for the force-electric coupling relationship is established. The statistical results show that both the acoustic emission and the charge signal accumulation have a significantly proportional relationship with the fractal dimension. Both the acoustic emission and charge signal reveal coal breakage evolution process, which will help in obtaining the precursor information on coal failure. Furthermore, the monitoring results can predict the extent of coal mass instability.

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Mechanical Properties of Bump‐Prone Coal with Different Porosities and Its Acoustic Emission‐Charge Induction Characteristics under Uniaxial Compression

Cited by 5 publications

References 37 publications

Research on the Failure Evolution Process of Rock Mass Base on the Acoustic Emission Parameters

Research on the Failure Evolution Process of Rock Mass Base on the Acoustic Emission Parameters

Review on Applications of X-ray Computed Tomography for Coal Characterization: Recent Progress and Perspectives

Analysis of Similarities and Differences between Acoustic Emission and Charge Signal Based on Fractal Characteristics of Coal Fracture

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