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Mining-induced stress-gas permeability characteristics based on protective layer pressure-relief mining
Kun Wang1,2,3, Xiangrui Meng2,3, Guangming Zhao1,2,3
1Key Laboratory of Safe and Effective Coal Mining Ministry of Education (Anhui University of Science and Technology), Ministry of Education, Anhui University of Science and Technology, Huainan, 232001, China.
Scientific Reports
|December 24, 2025
Summary
Protective layer pressure-relief mining enhances gas permeability in deep coal seams by creating stable seepage channels. Circumferential stress is key, influencing gas extraction efficiency and safety.
Area of Science:
- Mining Engineering
- Geomechanics
- Petroleum Engineering
Background:
- Protective layer pressure-relief mining is crucial for preventing coal and gas outbursts in deep seams.
- It also facilitates safe and efficient gas extraction from low-permeability coal.
Purpose of the Study:
- To elucidate the gas permeability mechanism of the protected layer under combined mining-induced stress and gas pressure during pressure-relief mining.
- To investigate the influence of axial and radial pressure-relief zones (APRZ and RPRZ) on gas permeability.
Main Methods:
- Permeation tests were conducted on APRZ and RPRZ using the ZST 1500 test system under various gas pressures.
- Analysis focused on the formation of seepage channels under axial stress, seepage pressure, and circumferential stress.
- A capillary-based permeability model was employed to fit experimental data.
Main Results:
- Axial stress and seepage pressure induced stable seepage channels.
- Radial pressure-relief zone (RPRZ) showed higher gas permeability than axial pressure-relief zone (APRZ).
- Gas permeability increased with decreasing circumferential stress, which was the predominant factor for channel formation.
Conclusions:
- Circumferential stress significantly impacts seepage channel formation and thus gas permeability.
- Gas slippage effect, influenced by seepage pressure, enhances permeability.
- The study provides a theoretical basis for optimizing gas drainage and co-extraction in mining.
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