Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study
Upper protective layer (UPL) mining is extensively utilised as a pressure relief strategy to prevent outbursts and coal bursts. However, when the excavation height of the protected layer is substantial, the depressurisation efficacy of the protective layer may be diminished. This paper takes the Hai...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-03-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/17/6/1446 |
| _version_ | 1797241238964928512 |
|---|---|
| author | Yanjiang Chai Linming Dou Jiang He Xiaotao Ma Fangzhou Lu Hu He |
| author_facet | Yanjiang Chai Linming Dou Jiang He Xiaotao Ma Fangzhou Lu Hu He |
| author_sort | Yanjiang Chai |
| collection | DOAJ |
| description | Upper protective layer (UPL) mining is extensively utilised as a pressure relief strategy to prevent outbursts and coal bursts. However, when the excavation height of the protected layer is substantial, the depressurisation efficacy of the protective layer may be diminished. This paper takes the Haishiwan coal mine in China as a case study and explores the stress evolution and influencing factors in the mining of extra-thick coal seam beneath the protective layer through theoretical analysis, numerical simulation, and field observation. The results indicate that increasing the excavation height of the coal seam will lead to the upward development of the collapse zone in the overburden of the goaf, with the “masonry beam” structure formed at a higher position by key strata blocks. The overburden above the masonry beam will be supported by the coal rock masse on both sides of the structure, leading to increased stress on the coal seam near the goaf and eliminating the depressurisation effect of the protective layer. Numerical simulation shows that factors such as faults, protective layers, interlayer spacing, and the height of coal seam excavation significantly affect the stress distribution in the protected layer. With the increase in interlayer spacing and the thickness of coal seam extraction, the stress reduction phenomenon of the UPL gradually decreases, especially with an abnormal stress concentration of the gob-side coal seam. Observations of Surface subsidence and the distribution of mining-induced seismic events corroborate the conclusions of theoretical analysis and numerical simulations. The results offer valuable guidance for the mining of extra-thick coal seams and the selection of the UPL. |
| first_indexed | 2024-04-24T18:20:09Z |
| format | Article |
| id | doaj.art-5202f2c474b94fe3ba04705d8bcc187c |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-24T18:20:09Z |
| publishDate | 2024-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-5202f2c474b94fe3ba04705d8bcc187c2024-03-27T13:35:46ZengMDPI AGEnergies1996-10732024-03-01176144610.3390/en17061446Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case StudyYanjiang Chai0Linming Dou1Jiang He2Xiaotao Ma3Fangzhou Lu4Hu He5School of Mines, China University of Mining and Technology, Xuzhou 221116, ChinaSchool of Mines, China University of Mining and Technology, Xuzhou 221116, ChinaSchool of Mines, China University of Mining and Technology, Xuzhou 221116, ChinaSchool of Mines, China University of Mining and Technology, Xuzhou 221116, ChinaSchool of Mines, China University of Mining and Technology, Xuzhou 221116, ChinaSchool of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, ChinaUpper protective layer (UPL) mining is extensively utilised as a pressure relief strategy to prevent outbursts and coal bursts. However, when the excavation height of the protected layer is substantial, the depressurisation efficacy of the protective layer may be diminished. This paper takes the Haishiwan coal mine in China as a case study and explores the stress evolution and influencing factors in the mining of extra-thick coal seam beneath the protective layer through theoretical analysis, numerical simulation, and field observation. The results indicate that increasing the excavation height of the coal seam will lead to the upward development of the collapse zone in the overburden of the goaf, with the “masonry beam” structure formed at a higher position by key strata blocks. The overburden above the masonry beam will be supported by the coal rock masse on both sides of the structure, leading to increased stress on the coal seam near the goaf and eliminating the depressurisation effect of the protective layer. Numerical simulation shows that factors such as faults, protective layers, interlayer spacing, and the height of coal seam excavation significantly affect the stress distribution in the protected layer. With the increase in interlayer spacing and the thickness of coal seam extraction, the stress reduction phenomenon of the UPL gradually decreases, especially with an abnormal stress concentration of the gob-side coal seam. Observations of Surface subsidence and the distribution of mining-induced seismic events corroborate the conclusions of theoretical analysis and numerical simulations. The results offer valuable guidance for the mining of extra-thick coal seams and the selection of the UPL.https://www.mdpi.com/1996-1073/17/6/1446thick coal seamprotective seamstress reductioninterlayer spacinginduced seismicity |
| spellingShingle | Yanjiang Chai Linming Dou Jiang He Xiaotao Ma Fangzhou Lu Hu He Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study Energies thick coal seam protective seam stress reduction interlayer spacing induced seismicity |
| title | Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study |
| title_full | Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study |
| title_fullStr | Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study |
| title_full_unstemmed | Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study |
| title_short | Limitations of Upper Protective Layers as Pressure Relief Measures for Extra-Thick Coal Seam Mining: Insights from a Case Study |
| title_sort | limitations of upper protective layers as pressure relief measures for extra thick coal seam mining insights from a case study |
| topic | thick coal seam protective seam stress reduction interlayer spacing induced seismicity |
| url | https://www.mdpi.com/1996-1073/17/6/1446 |
| work_keys_str_mv | AT yanjiangchai limitationsofupperprotectivelayersaspressurereliefmeasuresforextrathickcoalseammininginsightsfromacasestudy AT linmingdou limitationsofupperprotectivelayersaspressurereliefmeasuresforextrathickcoalseammininginsightsfromacasestudy AT jianghe limitationsofupperprotectivelayersaspressurereliefmeasuresforextrathickcoalseammininginsightsfromacasestudy AT xiaotaoma limitationsofupperprotectivelayersaspressurereliefmeasuresforextrathickcoalseammininginsightsfromacasestudy AT fangzhoulu limitationsofupperprotectivelayersaspressurereliefmeasuresforextrathickcoalseammininginsightsfromacasestudy AT huhe limitationsofupperprotectivelayersaspressurereliefmeasuresforextrathickcoalseammininginsightsfromacasestudy |