Mechanical properties and impact energy index of coal affected by gas pressure and evolutionary mechanism

Authors

DING Xin, School of Mechanics and Engineering, Liaoning Technical University, Fuxin 123000, ChinaFollow
XIAO Xiaochun, School of Mechanics and Engineering, Liaoning Technical University, Fuxin 123000, ChinaFollow
PAN Yishan, School of Mechanics and Engineering, Liaoning Technical University, Fuxin 123000, China; School of Environment, Liaoning University, Shenyang 110136, China

Abstract

The frequent occurrence of gas emission and outburst accidents caused by rock bursts in deep coal seams poses a great threat to safe underground production. Therefore, clarifying the evolution law of the mechanical properties and burst potential of gas on coal and rock is the basis for establishing effective prevention and control measures. Using the self-developed visual coal fluid-solid coupling test system, we carried out the physical experiment to study the gas adsorption, mechanical properties and fragment distribution of coal affected by gas pressure, and analyzed the evolution characteristics and mechanism of the bursting energy index. The results show that the gas isotherm adsorption curve of coal with strong burst potential conforms to the Langmuir model. With the increase of gas pressure, the softening characteristics become more obvious, the elastic modulus and the softening modulus decrease in stages, where the gas has different effects on them before and after the stress peak of coal and there is a critical pressure. The impact energy index and the fragment size of the samples show a “V” type change characteristic of first decreasing and then increasing. Their failure modes are “brittle tension → shear → tension + plastic flow”, and there is more surplus energy after fragmentation. The small-scale fragments of gas-bearing coal are the objective condition for disaster occurrence. The gas expansion energy provides additional energy for the dynamic instability of coal mass, which increases the strong dynamic and destructive nature of the occurrence process of rock bursts, and the solid-fluid coupling of coal matrix framework and gas migration reduces the critical index and has a higher disaster-causing potential. The research results and enlightenment provide an experimental basis and ideas for accurately determining the catastrophic liability of deep coal seams with high gas pressure, and develope effective prevention and control methods.

Keywords

coal mechanical property, bursting energy index, rock burst, coal seam with high gas pressure, gas adsorption characteristics, fractal dimension

DOI

10.12363/issn.1001-1986.21.11.0692

Recommended Citation

DING Xin, XIAO Xiaochun, PAN Yishan, et al. (2022) "Mechanical properties and impact energy index of coal affected by gas pressure and evolutionary mechanism," Coal Geology & Exploration: Vol. 50: Iss. 7, Article 13.
DOI: 10.12363/issn.1001-1986.21.11.0692
Available at: https://cge.researchcommons.org/journal/vol50/iss7/13

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