Degradation mechanism of coal pillars in an underground coal gasification environment: Bearing capacity, pyrolysis behaviour and pore structure
Coal pillars are critical supporting structures between underground coal gasification gasifiers. Its bearing capacity and structural stability are severely threatened by high-temperature environments. To elucidate the high-temperature deterioration mechanism of coal pillars at multiple scales, coal...
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Elsevier
2025-06-01
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| Series: | International Journal of Mining Science and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2095268625000771 |
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| author | Jian Li Jinwen Bai Guorui Feng Erol Yilmaz Yanna Han Zhe Wang Shanyong Wang Guowei Wu |
| author_facet | Jian Li Jinwen Bai Guorui Feng Erol Yilmaz Yanna Han Zhe Wang Shanyong Wang Guowei Wu |
| author_sort | Jian Li |
| collection | DOAJ |
| description | Coal pillars are critical supporting structures between underground coal gasification gasifiers. Its bearing capacity and structural stability are severely threatened by high-temperature environments. To elucidate the high-temperature deterioration mechanism of coal pillars at multiple scales, coal strength features as a function of temperature were investigated via uniaxial compression and acoustic emission equipment. The pyrolysis reaction process and microstructure evolution were characterized via X-ray diffractometer (XRD), scanning electron microscope (SEM), thermogravimetric (TG), Fourier transform infrared spectroscopy (FTIR), and computed tomography (CT) tests. Experimental results reveal a critical temperature threshold of 500 °C for severe degradation of the coal bearing capacity. Specifically, both the strength and elastic modulus exhibit accelerated degradation above this temperature, with maximum reductions of 45.53% and 61.34%, respectively. Above 500 °C, coal essentially undergoes a pyrolysis reaction under N2 and CO2 atmospheres. High temperatures decrease the quantity of O2-based functional groups, growing aromaticity and the degree of graphitization. These changes induce dislocation and slip inside the coal crystal nucleus and then lead to deformation of the coal molecular structural units and strain energy generation. This process results in a great increase in porosity. Consequently, the stress deformation of coal increases, transforming the type of failure from brittle to ductile failure. These findings are expected to provide scientific support for UCG rock strata control. |
| format | Article |
| id | doaj-art-536d0e42df1b465eb8744980e4b45d52 |
| institution | DOAJ |
| issn | 2095-2686 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal of Mining Science and Technology |
| spelling | doaj-art-536d0e42df1b465eb8744980e4b45d522025-08-20T03:17:46ZengElsevierInternational Journal of Mining Science and Technology2095-26862025-06-0135689791210.1016/j.ijmst.2025.05.002Degradation mechanism of coal pillars in an underground coal gasification environment: Bearing capacity, pyrolysis behaviour and pore structureJian Li0Jinwen Bai1Guorui Feng2Erol Yilmaz3Yanna Han4Zhe Wang5Shanyong Wang6Guowei Wu7College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China; Key Laboratory of Shanxi Province for Mine Rock Strata Control and Disaster Prevention, Taiyuan University of Technology, Taiyuan 030024, China; Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan 030024, ChinaCollege of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China; Key Laboratory of Shanxi Province for Mine Rock Strata Control and Disaster Prevention, Taiyuan University of Technology, Taiyuan 030024, China; Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan 030024, China; Corresponding authors.College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China; Key Laboratory of Shanxi Province for Mine Rock Strata Control and Disaster Prevention, Taiyuan University of Technology, Taiyuan 030024, China; Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan 030024, China; Corresponding authors.Department of Civil Engineering, Geotechnical Division, Recep Tayyip Erdogan University, Fener, Rize TR53100, TurkeyCollege of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China; Key Laboratory of Shanxi Province for Mine Rock Strata Control and Disaster Prevention, Taiyuan University of Technology, Taiyuan 030024, China; Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan 030024, ChinaCollege of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaPriority Research Centre for Geotechnical Science and Engineering, School of Engineering, The University of Newcastle, Callaghan, NSW 2308, AustraliaCollege of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China; Key Laboratory of Shanxi Province for Mine Rock Strata Control and Disaster Prevention, Taiyuan University of Technology, Taiyuan 030024, China; Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan 030024, ChinaCoal pillars are critical supporting structures between underground coal gasification gasifiers. Its bearing capacity and structural stability are severely threatened by high-temperature environments. To elucidate the high-temperature deterioration mechanism of coal pillars at multiple scales, coal strength features as a function of temperature were investigated via uniaxial compression and acoustic emission equipment. The pyrolysis reaction process and microstructure evolution were characterized via X-ray diffractometer (XRD), scanning electron microscope (SEM), thermogravimetric (TG), Fourier transform infrared spectroscopy (FTIR), and computed tomography (CT) tests. Experimental results reveal a critical temperature threshold of 500 °C for severe degradation of the coal bearing capacity. Specifically, both the strength and elastic modulus exhibit accelerated degradation above this temperature, with maximum reductions of 45.53% and 61.34%, respectively. Above 500 °C, coal essentially undergoes a pyrolysis reaction under N2 and CO2 atmospheres. High temperatures decrease the quantity of O2-based functional groups, growing aromaticity and the degree of graphitization. These changes induce dislocation and slip inside the coal crystal nucleus and then lead to deformation of the coal molecular structural units and strain energy generation. This process results in a great increase in porosity. Consequently, the stress deformation of coal increases, transforming the type of failure from brittle to ductile failure. These findings are expected to provide scientific support for UCG rock strata control.http://www.sciencedirect.com/science/article/pii/S2095268625000771Thermal damageCoal pillarBearing characteristicsPyrolysisUnderground coal gasification |
| spellingShingle | Jian Li Jinwen Bai Guorui Feng Erol Yilmaz Yanna Han Zhe Wang Shanyong Wang Guowei Wu Degradation mechanism of coal pillars in an underground coal gasification environment: Bearing capacity, pyrolysis behaviour and pore structure International Journal of Mining Science and Technology Thermal damage Coal pillar Bearing characteristics Pyrolysis Underground coal gasification |
| title | Degradation mechanism of coal pillars in an underground coal gasification environment: Bearing capacity, pyrolysis behaviour and pore structure |
| title_full | Degradation mechanism of coal pillars in an underground coal gasification environment: Bearing capacity, pyrolysis behaviour and pore structure |
| title_fullStr | Degradation mechanism of coal pillars in an underground coal gasification environment: Bearing capacity, pyrolysis behaviour and pore structure |
| title_full_unstemmed | Degradation mechanism of coal pillars in an underground coal gasification environment: Bearing capacity, pyrolysis behaviour and pore structure |
| title_short | Degradation mechanism of coal pillars in an underground coal gasification environment: Bearing capacity, pyrolysis behaviour and pore structure |
| title_sort | degradation mechanism of coal pillars in an underground coal gasification environment bearing capacity pyrolysis behaviour and pore structure |
| topic | Thermal damage Coal pillar Bearing characteristics Pyrolysis Underground coal gasification |
| url | http://www.sciencedirect.com/science/article/pii/S2095268625000771 |
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