A new experimental apparatus for sudden unloading of gas-bearing coal

Wang, Gang; Guo, Yangyang; Wang, Pengfei; Li, Wenxin; Wu, Mengmeng; Sun, Lulu; Cao, Jianjun; Du, Changang

doi:10.1007/s10064-019-01601-3

Cited by 23 publications

(12 citation statements)

References 19 publications

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“…Wang et al. studied the deformation characteristics of coal samples after the sudden release of high‐pressure gas by a special device, and pointed out that the plastic deformation of coal samples under high‐pressure can be divided into three stages: compression, expansion and deformation, which provides a reference for researching the elastic properties of outburst 16 . Wang and Cheng confirmed via experiments that the elastic energy release mode of tectonic coal is different from that of intact coal, and established a new model for the whole process, and determined that the pre‐release of deformation energy of tectonic coal is necessary for the accumulation of gas expansion energy and the outburst triggering 17 …”

Section: Introductionmentioning

confidence: 99%

Experimental study on the outburst potential energy caused by added water under stepwise depressurization

Li,

Chen,

Wang

et al. 2024

Greenhouse Gases

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The research on the mechanism of coal and gas outburst is still in the hypothesis stage, and exploration of the outburst mechanism fro m an energy perspective often focuses on the calculation of coal rock elastic energy and gas expansion energy. There are some studies on elastic energy and gas expansion energy of coal rock caused by added water during outburst, although hydr aulic measures not only improve the permeability of coal seam, but also increase the water content. For calculating the gas expansion energy, the atmospheric gas desorption characteristic is generally utilized, while the gas desorption is completed on the condition of dropping pressure in outburst, and the expansion energy research, based on that law, inevitably brings about errors, thus affecting the objectivity of the potential research. In this study, uniaxial cyclic loading experiments were carried out on briquette coal samples with water content of 0%, 1%, 2% and 4%, whose elastic energy density was analyzed, in addition to examining how the added water affected the mechanical properties and the elastic energy of coal. The pressure drop gradient of the experiment is set 2.5 –2 MPa, 1.5 –1 MPa, 0.5 MPa‐0 Pa. By stepwise depressurization desorption of coal samples after water injection, the gas expansion energy in different moisture is measured in each pressure drop stage, and the influence of moisture on gas expansion energy is quantitatively explored. Research has shown that the higher the water content, the lower the elastic energy density, while the higher the stress, the greater the elastic energy of coal. The gas expansion energy grows linearly with the increase of adsorption equilibrium pressure and diminishes in negative exponential law with the increasing moisture. Under the experimental conditions, the expansion energy decreases by 7%–9% and the elastic energy by 9.7% on average for every 1% increase in added water, and the influence gradually weakens when the moisture exceeds the critical value. This study innovatively simulates the pressure swing desorption when a coal and gas outburst occurs in the laboratory, confirms the critical moisture that affects the outburst potential, and is a useful exploration in the coal and gas outburst mechanism. Significantly the research results can guide the engineering practice when using hydraulic measures to prevent and control outburst disasters. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

Experimental study on the outburst potential energy caused by added water under stepwise depressurization

Li,

Chen,

Wang

et al. 2024

Greenhouse Gases

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“…However, there is still a lack of a clear understanding of the outburst mechanism because of its complexity. 8,9 Due to the disastrous and accidental nature of coal and gas outbursts, it is challenging to observe outbursts in the field. Therefore, the experimental and numerical simulations had become the effective means to research the coal and gas outbursts and the mechanical mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism research on coal and gas outbursts is generally regarded as a vital part of outburst prevention and control. However, there is still a lack of a clear understanding of the outburst mechanism because of its complexity. , …”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Coal and Gas Outbursts under Different In Situ Stresses and Gas Pressures and the Physical Characteristics of Coal

et al. 2021

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The coal and gas outbursts are recognized as a worldwide difficulty, and there is still ample research space in this field, especially on the mechanical mechanism of outbursts. The main purpose of this paper is to attempt to reveal the outburst mechanism as fully as possible from the point of view of mechanics. In this paper, a mechanical model on coal and gas outbursts including the governing equations of gas desorption–seepage, the stress state in the coal sample, and the criteria of coal sample failure and outburst evolution is put forward according to the porous media seepage theory and elastic theory. Based on the proposed model, the variation and distribution of the gas state and stress state in the coal sample in the outburst are analyzed quantitatively and a series of detailed discussions are conducted in terms of the in-situ stress, gas pressure, and the physical characteristics of coal in outbursts. The results of theoretical analysis and numerical simulation show that the stress concentration in the front of the outburst cavity is the main reason for the failure of the coal sample in this area, and then, the drag force caused by gas flow provides energy for the movement of the crushed coal sample, which leads to the outburst cavity expansion and the increase of stress concentration factor. The end of the outburst is because the gas velocity is less than the threshold friction velocity of the crushed coal sample. Additionally, the outburst strength increases with the increase of the vertical in-situ stress and initial gas pressure and decreases with the increase of the internal friction angle and cohesion of coal.

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“…Ground stress has been considered as the fundamental force causing deformations and damages in various underground excavation projects [1,2] and one of the important bases for designing the support and protection system of the underground projects. Ground stress has been divided into two categories including self-weight stress and horizontal tectonic stress.…”

Section: Introductionmentioning

confidence: 99%

An Analysis of the Impact of Deviatoric Stress and Spherical Stress on the Stability of Surrounding Rocks in Roadway

Liu

Zhu

2021

Geofluids

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In this study, a detailed analysis was conducted to evaluate the impacts of the deviatoric stress component and spherical stress component on the stability of surrounding rocks in the roadway via the theoretical analysis and calculation and numerical simulation. Based on the analysis, the distribution laws guiding the main stress differences, plastic zone, convergence of surrounding rocks, and third invariant of stress under various conditions (such as equal spherical stress and unequal deviatoric stress and equal deviatoric stress and unequal spherical stress) were developed, providing an optimization scheme for roadway support misunderstanding under the conditions of high spherical stress field and high deviator stress field. The study further reveals that under the circumstance of the constant spherical stress, the greater the deviatoric stress, the plastic zone range of the surrounding rock of the roadway, the range of tensile deformation of the surrounding rock, the amount of convergence of the surrounding rock, the probability of separation of the roof and floor of the roadway, and the principal stress difference and the main stress, the greater the concentration range of the maximum stress difference is, and the maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway, and the greater the deviatoric stress, the greater the probability that the roof and floor rocks of the roadway will be separated, and the maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway, the greater the deviator stress, the greater the concentration range of the maximum value of the principal stress difference and the principal stress difference; when the deviator stress is constant, the range of the plastic zone and the maximum principal stress difference concentration range of the surrounding rock of the roadway decrease with the increase of the ball stress, and the principal stress difference, the amount of convergence of the surrounding rock, and the range of tensile deformation increase with the increase of the ball stress. The maximum principal stress difference is mainly concentrated in the roof and floor rocks of the roadway. The principal stress difference increases with the increase of the spherical stress, and the maximum concentration range of the principal stress difference decreases with the increase of the spherical stress. After the method proposed in this paper optimizes the actual roadway support on site, the surrounding rock deformation of the roadway is small and the control is relatively ideal, which basically meets the engineering needs.

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A new experimental apparatus for sudden unloading of gas-bearing coal

Cited by 23 publications

References 19 publications

Experimental study on the outburst potential energy caused by added water under stepwise depressurization

Experimental study on the outburst potential energy caused by added water under stepwise depressurization

Numerical Investigation of Coal and Gas Outbursts under Different In Situ Stresses and Gas Pressures and the Physical Characteristics of Coal

An Analysis of the Impact of Deviatoric Stress and Spherical Stress on the Stability of Surrounding Rocks in Roadway

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