Failure Characterization of Three Typical Coal-Bearing Formation Rocks Using Acoustic Emission Monitoring and X-ray Computed Tomography Techniques

Zhang, R.; Ai, Ting; Ren, Li; Li, G.

doi:10.1007/s00603-018-1677-9

Cited by 30 publications

(6 citation statements)

References 39 publications

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“…Additionally, Zhang et al discovered that the energy released during the main fracture stage for most rocks contributed the largest proportion of the total energy released over the entire loading process. 40 This is consistent with the phenomenon that the energy of Type V AE signals is approximately 100 times that of other types of AE signals.…”

Section: Qualitative Characteristics Of Different Types Of Ae Signalssupporting

confidence: 86%

Experimental study on failure precursors of coal and sandstone based on two‐step clustering of acoustic emission characteristics

Zheng,

Liang,

et al. 2023

Energy Science & Engineering

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Accurately determining the precursors of coal and rock failures is crucial for preventing associated risks in coal mines. In this study, based on the values of the four parameters amplitude, duration, counts and energy of acoustic emission (AE) signals, the AE signals of coal and sandstone samples failure were clustered by the two‐step clustering method. And the precursory AE signals of sample failure under uniaxial compression were analyzed and identified. Results show that the peak of AE amplitude is before that of AE duration, counts, and energy. AE signals of both coal and sandstone samples can be classified into five types. Values of the parameters of Types I–IV AE signals of the sandstone sample are lower than that of the coal sample. The duration, counts, and energy of Type V AE signals of the sandstone sample are higher than that of the coal sample. Type V AE signals, which are middle amplitude (hundreds of mV), high duration (hundreds of thousands of μS), high counts (about 10,000), and high energy (tens of thousands of mV*mS), account for the lowest proportion of all AE signals, at approximately 0.1%. And they began to occur at 87% σc of the coal sample and at 97% σc of the sandstone sample, respectively. Type V AE signals can be used as precursors of coal and sandstone samples failure under uniaxial compression.

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Section: Qualitative Characteristics Of Different Types Of Ae Signalssupporting

confidence: 86%

Experimental study on failure precursors of coal and sandstone based on two‐step clustering of acoustic emission characteristics

Zheng,

Liang,

et al. 2023

Energy Science & Engineering

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“…To date, considerable research efforts have been devoted to exploring the physical and mechanical properties of numerous types of rocks, and the influences of different factors (e.g. confining pressure, water content, and temperature) on the mechanical behavior of rocks (Cai, 2010;Liu et al, 2014;Sainsbury and Sainsbury, 2017;Xia et al, 2017;Xu et al, 2017b;Xue et al, 2018;Zhang et al, 2018bZhang et al, , 2018d. Bian et al (2019) explored the water-weakening effect to shale specimens with distinct immersion time and proposed a damage constitutive model for rock water-weakening effect.…”

Section: Introductionmentioning

confidence: 99%

Study on mechanical properties and damage evolution of carbonaceous shale under triaxial compression with acoustic emission

Yang

Yan

Zhang

et al. 2021

International Journal of Damage Mechanics

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To explore the mechanical properties and damage evolution characteristics of carbonaceous shale with different confining pressures and water-bearing conditions, triaxial compression tests accompanied by simultaneous acoustic emission (AE) monitoring were conducted on carbonaceous shale rock specimens. The AE characteristics of carbonaceous shale were investigated, a damage assessment method based on Shannon entropy of AE was further proposed. The results suggest that the mechanical properties of carbonaceous shale intensify with increasing confining pressure and degrade with increasing water content. Moisture in rocks does not only weaken the cohesion but also reduce the internal friction angle of carbonaceous shale. It is observed that AE activities mainly occur in the post-peak stage and the strong AE activities of saturated carbonaceous shale specimens appear at a lower normalized stress level than that of natural-state specimens. The maximum AE counts and AE energy increase with water content while decrease with confining pressure. Both confining pressure and water content induce changes in the proportions of AE dominant frequency bands, but the changes caused by confining pressure are more significant than those caused by water content. The results also indicate that AE entropy can serve as an applicable index for rock damage assessment. The damage evolution process of carbonaceous shale can be divided into two main stages, including the stable damage development stage and the damage acceleration stage. The damage variable increases slowly accompanied by a few AE activities at the first stage, which is followed by a rapid growth along with intense acoustic emission activities at the damage acceleration stage. Moreover, there is a sharp rise in the damage evolution curve for the natural-state specimen at the damage acceleration stage, while the damage variable develops slowly for the saturated-state specimen.

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“…Li et al used high-frequency AE to monitor true triaxial hydraulic fracturing of coal. Zhang et al , used AE in the experiments of coal-bearing rocks and different types of coal to detect the generation of microcracks and the evolution of macroscopic and microscopic failures. Hao et al obtained 3D reconstructed coal samples by CT scanning of bituminous coal with different water contents.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Fracture Network Expansion Mechanism and Three-Dimensional Reconstruction Characteristic of High-Rank Coal in Guizhou Province, China

et al. 2023

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To better understand the fracture propagation characteristics and spatial distribution pattern of a high-rank coal reservoir during hydraulic fracturing, a true triaxial physical simulation device was used to conduct a hydraulic fracturing experiment on large-sized raw coal from Zhijin, Guizhou Province, China. Computed tomography technology was used to scan the three-dimensional morphology of the fracture network before and after fracturing, then AVIZO software was used to reconstruct the internal fractures of the coal sample, and fractal theory was used to quantify the fractures. The results show that (1) the sudden increase of the pump pressure curve and acoustic emission signal is an important identification feature of hydraulic fractures, and the in situ stress difference coefficient plays a leading role in the complexity of coal and rock fractures. (2) When a hydraulic fracture encounters a primary fracture in the process of expansion, the opening of the primary fracture, the penetration, bifurcation, and turning of the hydraulic fracture are the main reasons for the formation of complex fractures, and the existence of a large number of primary fractures is the basis for the formation of complex fractures. (3) The fracture shape of coal hydraulic fracturing can be divided into three categories: complex fracture, plane fracture + cross fracture, and inverted T-shaped fracture. The fracture shape is closely related to the original fracture shape. The research results of this paper provide strong theoretical and technical support for coalbed methane mining design such as Zhijin high-rank coal reservoirs.

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Failure Characterization of Three Typical Coal-Bearing Formation Rocks Using Acoustic Emission Monitoring and X-ray Computed Tomography Techniques

Cited by 30 publications

References 39 publications

Experimental study on failure precursors of coal and sandstone based on two‐step clustering of acoustic emission characteristics

Experimental study on failure precursors of coal and sandstone based on two‐step clustering of acoustic emission characteristics

Study on mechanical properties and damage evolution of carbonaceous shale under triaxial compression with acoustic emission

Experimental Study of the Fracture Network Expansion Mechanism and Three-Dimensional Reconstruction Characteristic of High-Rank Coal in Guizhou Province, China

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