Piezoelectric effect and ignition properties of coal mine roof sandstone deformation and fracture

Li, Min; Lü, Yi; Shi, Shiliang; Li, He; Tian, Zhaojun; Ye, Qing; Lu, Jiexin

doi:10.1016/j.fuel.2020.120007

Cited by 29 publications

(17 citation statements)

References 27 publications

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“…All the coal-like samples had at least one crack along the axial direction through the entire sample. The failure mode of the sample was mainly a tensile failure, supplemented by shear failure, and accompanied by local spallation on the surface of the sample because the tensile strength was much lower than the compressive strength . It can also be concluded that the failure complexity of the sample decreased with increasing coal particle size in uniaxial compression experiments.…”

Section: Resultsmentioning

confidence: 94%

Experimental Study on the Effect of Coal Particle Size on the Mechanics, Pore Structure, and Permeability of Coal-like Materials for Low-Rank Coalbed Methane Reservoir Simulation

Zheng

Zhai

et al. 2021

Energy Fuels

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Coal-like materials have been widely used to simulate low-rank coalbed methane (CBM) reservoirs to develop fracturing stimulation technology since the transportation and preparation of low-rank coal produce easily secondary damages, causing large dispersion of test results. However, the coal particle sizes have a significant effect on the performance of coal-like materials among many factors. Hence, to accurately simulate lowrank CBM reservoirs for promoting the development of reservoir stimulation technologies, cement, gypsum, pulverized coal, and sand were selected as similar materials to make coal-like samples with different coal particle sizes to study the influence law of coal particle size on the mechanics, pore structure, and permeability of samples. The ultrasonic wave velocity, dynamic parameters, uniaxial compressive strength, elastic modulus, and uniaxial tensile strength of samples increased with increasing coal particle size in the range of 0−2 mm. However, these parameters suddenly decreased when the coal particle size increased to 2−3 mm. The porosity and permeability of the samples exhibited an opposite trend compared to the above parameters. The fracture occurred in cementing materials, and the crack extension direction was affected by the coal particle sizes. The fracture complexity of the coal-like samples decreased with increasing particle size under uniaxial compressive testing. The failure mode was mainly a tensile failure, supplemented by shear failure. The coal-like materials can well meet the performance requirements of low-rank CBM reservoirs.

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Section: Resultsmentioning

confidence: 94%

Experimental Study on the Effect of Coal Particle Size on the Mechanics, Pore Structure, and Permeability of Coal-like Materials for Low-Rank Coalbed Methane Reservoir Simulation

Zheng

Zhai

et al. 2021

Energy Fuels

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“…During the period of elastoplastic deformation, the surface potential and current are generated by electric dipoles concentrated on the surface of the microcracks [4]. In the fracture process of the sandstone roof, a strong instant discharge, resulting from a piezoeffect, caused an electrical breakdown of air [5]. The signal of the electric potential may reflect the state of the load and the evolution in the fracture of the coal massif and it can be considered as a forerunner of the occurrence of dynamic fracture [6].…”

Section: Introductionmentioning

confidence: 99%

Research of the quasistable self-potential effect of highly-metamorphic coal in laboratory conditions

Bezruchko

Burchak

Balalaiev

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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The article focuses on a quasistable electrical potential registered on samples of highly-metamorphic and high-ash coal in normal laboratory conditions. The purpose of the study is to determine the possible conditions for the appearance of their effect in the coal and carbon-like argillite and the parameters of its structure. The appearance of an uncompensated charge is not associated with thermoelectric and electrokinetic phenomena and it has not been previously described. Most samples are characterized by an uneven distribution of charges along the surface in the form of a polydomain structure. Polarized samples have a layered coal-mineral structure. The charge magnitude depends on the thickness and density of the layers. In heterogeneous and heterophase substances the Maxwell-Wagner polarization is realized, arising on the boundary layers of dielectric micrograins of various substances, as well as between the areas of one dielectric with an amorphous and crystalline phase. Microinclusions and anthracite layers, which increase the potential ability of mineral components to their own polarization, can be conductors. Charged samples may have a stable, non-compensated monodomain residual charge under constant external conditions, which is characteristic of the electrets. The detected effect can be useful when creating alternative devices accumulating electricity.

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“…The methane storage capacity of coal is affected by multiple internal and external factors, such as pore size distributions across the thermal evolution of coal from peat to anthracite, temperature, and pressure 10–13 . In terms of the pore structure of coal, previous studies have found that the number of micropores plays an important role in methane adsorption capacity 14–16 . On this basis, Zhou et al 17 .…”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12][13] In terms of the pore structure of coal, previous studies have found that the number of micropores plays an important role in methane adsorption capacity. [14][15][16] On this basis, Zhou et al 17 found that the adsorbed methane is stored not only in micropores but also in meso-macropores. However, most of previous researches were conducted in an environment where the maximum pressure was less than 6 MPa and room temperature.…”

mentioning

confidence: 99%

Evaluation and analysis of methane adsorption capacity in deep‐buried coal seams

et al. 2022

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In this work, the high‐pressure methane adsorption/desorption tests were conducted in four coal samples (from low‐rank bituminous coal to anthracite) under different temperature and pressure conditions to reveal the mechanism of desorption hysteresis effect in the deep‐buried coal seams. The experimental and fitting results show that the presence of free methane molecules in the adsorption phase results in an obvious difference between the measured methane adsorption amount with the actual adsorption capacity. The Langmuir, Langmuir–Freundlich (L–F) and Dubinin–Astakhov (D–A) models have their own advantages and disadvantages in fitting the experimental adsorption/desorption data. As residual adsorption capacity C fitted by the D–A model would be negative at high temperatures and lose the meaning of the constant, the Langmuir model is more suitable to describe methane desorption process. The residual adsorption capacity fitted by Langmuir model tended to decrease as the temperature increased until it is almost completely desorbed at 373 K. Meanwhile, because the adsorption sites with lower energy are gradually occupied by methane molecules in the high‐pressure stage, intermolecular forces increased and methane molecules are more easily desorbed. Therefore, the desorption hysteresis coefficient trends to increase exponentially with the decrease of pressure and temperature, which indicated that the original gas content of the coal seams may decrease with the increase of the burial depth, but the risk of coal and gas outburst accidents may increase. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Piezoelectric effect and ignition properties of coal mine roof sandstone deformation and fracture

Cited by 29 publications

References 27 publications

Experimental Study on the Effect of Coal Particle Size on the Mechanics, Pore Structure, and Permeability of Coal-like Materials for Low-Rank Coalbed Methane Reservoir Simulation

Experimental Study on the Effect of Coal Particle Size on the Mechanics, Pore Structure, and Permeability of Coal-like Materials for Low-Rank Coalbed Methane Reservoir Simulation

Research of the quasistable self-potential effect of highly-metamorphic coal in laboratory conditions

Evaluation and analysis of methane adsorption capacity in deep‐buried coal seams

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