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Mechanisms of Coal and Gas Outburst Experiments: Implications for the Energy Principle of Natural Outbursts.

Authors :
Lei, Yang
Cheng, Yuanping
Wang, Liang
Ren, Ting
Tu, Qingyi
Source :
Rock Mechanics & Rock Engineering; Jan2023, Vol. 56 Issue 1, p363-377, 15p
Publication Year :
2023

Abstract

Coal and gas outbursts in underground mines are the result of dynamic rupture propagation along coal seams, starting from localized instability caused by the sudden release of gas and strain energies. Although physical simulations have facilitated quantitative studies of outbursts, and rupture processes have been investigated both experimentally and theoretically, the underlying mechanisms responsible for triggering outbursts remain poorly understood. This lack of understanding seriously limits our ability to prevent gas hazards. Here we systematically analyze the essential characteristics and energy principles of outburst experiments over the past 70 years and explore the onset of natural outbursts. The results show that although laboratory experiments and natural events are dynamically similar, their triggering mechanisms are fundamentally different. Specifically, actual outbursts depend highly on stress conditions and gas desorption; in contrast, experiments can be performed under stress-free conditions or even entirely dominated by free gas, often with low threshold pressures (< 0.7 MPa). Energy analysis indicated that the high porosity of the experimental briquette resulted in much higher free gas energy than in the actual coal seam (up to ~ 40 times), enabling the simulated outbursts to overcome mechanical barriers easily and, in turn, to be stress independent. Furthermore, our findings suggest that the triggering process of a natural outburst is unlikely to be transient. Instead, the development of fractures and the consequent enlargement of free gas energy are essential processes for initiating ruptures and generating potential precursors. Our results highlight that understanding the role of gas and stress is crucial for accurately interpreting outburst mechanisms. Highlights: The essential characteristics and energy principles of outburst experiments were systematically analyzed. Outburst experiments are fundamentally different from natural events in triggering mechanisms. Outburst simulations are essentially free gas-driven dynamics. Fracture development and increased free gas energy are necessary processes to initiate ruptures. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
07232632
Volume :
56
Issue :
1
Database :
Complementary Index
Journal :
Rock Mechanics & Rock Engineering
Publication Type :
Academic Journal
Accession number :
161551318
Full Text :
https://doi.org/10.1007/s00603-022-03093-2