Multiphysics Coupling Analysis of Indicator Gas Variations Induced by Coal Spontaneous Combustion in Longwall Goaf

Understanding the self-heating behaviour and distribution patterns of indicator gases within longwall goaf is critical for preventing coal mine spontaneous combustion (sponcom). In prior studies, coal self-heating temperature and variations of gas products are often analysed independently, making it challenging to comprehensively reveal their dynamic interrelations. Moreover, the gas emission patterns observed under laboratory conditions are difficult to directly extrapolate to the field environment of a longwall goaf. To address these challenges, this study integrates Multiphysics coupled modelling with experimental analysis. Firstly, a Multiphysics coupling model is developed to represent the interactions among solid, gas, and thermal processes within the goaf. This model systematically investigates the coupling mechanisms between temperature and gas distributions during coal self-heating, along with their spatiotemporal evolution characteristics. Based on this model, a coal oxidation model incorporating gas products of C2H4 and C2H6 as sponcom gas indicators is introduced, informed by laboratory experimental results. By integrating these two models, this research comprehensively explores the relationships among temperature, gas concentrations, and coal properties during sponcom. The results demonstrate that temperature gradients drive the migration and accumulation of indicator gases, and the sponcom process exhibits a pronounced localisation trend. Combined experimental and numerical simulation findings elucidate the coupling laws governing temperature fields and gas distributions, providing a scientific basis for optimising gas monitoring systems and enhancing the accuracy of identifying coal sponcom. In summary, this thesis establishes an integrated coal sponcom model that captures the coupled evolution of temperature fields and indicator gas behaviours. By revealing the dynamic correlation between temperature variations and gas concentration patterns, it provides a theoretical basis for optimising the layout of gas and temperature monitoring systems, particularly enhancing the placement of Tube Bundle Systems and other gas detection devices. These findings offer practical guidance for improving early warning accuracy and understanding indicator gas evolution during sponcom development, with direct implications for advancing mine safety management.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2025

Author dc:creator

• Wu, Xuebin

• coal spontaneous combustion
• Multiphysics coupling
• Indicator gases system
• Mine ventilation
• anzsrc-for: 401905 Mining engineering

Statement dc:rights

• open access
• CC BY 4.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by/4.0/

Identifier

https://doi.org/10.26190/unsworks/31184

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/105063