An experiment to determine the width of coal pillar when mining seams under hard-to-cave main roof conditions

  • Affiliations:

    Hanoi University of Mining and Geology, Hanoi, Vietnam

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  • Received: 24th-Dec-2023
  • Revised: 8th-Mar-2024
  • Accepted: 21st-Mar-2024
  • Online: 1st-Apr-2024
Pages: 47 - 55
Views: 359
Downloads: 3
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Ensuring roadway stability is one of the keys to determining production efficiency and labor safety in Vietnam's underground coal mines. However, it is difficult to determine the reasonable width of coal pillars to protect the roadway and roadway deformation therefore usually occurs. Especially when exploiting coal seams in the deep and hard main roof conditions, the deformation of the roadway becomes even more serious, affecting labor safety. Using the mining data of Seam #10 at Ha Long Coal Company as the reference case of this research, a scale model of equivalent materials has been conducted. The stability of the roadway has been simulated and analyzed in different widths of coal pillars. The results show that, when exploiting coal seams under a hard-to-cave roof, very thick and long roof consoles are formed in the gob. The stability of the coal pillar and roadway is influenced by the sagging, rotation, and fracturing of the main roof in the gob. Under the impact of static and dynamic loads of the main roof, a coal pillar of less than 40 m width is not stable enough to protect the roadway. As the width of the coal pillar decreases, more apparent cracks in the roadway roof appear, and the coal blocks on the walls of the roadway are broken and wider. Visual monitoring results show that a coal pillar of more than 40 m in width can ensure the stability of the roadway. However, it causes a much more loss of coal in the pillars, a challenge for further research.

How to Cite
Le, P.Quang, Dao, C.Van, Bui, T.Manh, Nguyen, H.Phi and Vu, D.Tien Thai 2024. An experiment to determine the width of coal pillar when mining seams under hard-to-cave main roof conditions. Journal of Mining and Earth Sciences. 65, 2 (Apr, 2024), 47-55. DOI:

Esterhuizen, E., Mark, C., and Murphy, M. M. (2010, July). Numerical model calibration for simulating coal pillars, gob and overburden response. In Proceedings of the 29th international conference on ground control in mining (pp. 46-57). Morgantown: West Virginia University. NIOSH/mining/UserFiles/works/pdfs/nmcfs.pdf.

Fan, N., Wang, J., Zhang, B., Liu, D., and Wang, R. (2020). Reasonable width of segment pillar of fully-mechanized caving face in inclined extra-thick coal seam. Geotechnical and Geological Engineering, 38, 4189-4200.

Hongtao, L. I. U., Xiangye, W. U., Zhen, H. A. O., Xidong, Z. H. A. O., and Xiaofei, G. U. O. (2017). Evolution law and stability control of plastic zones of retained entry of working face with double roadways layout. Journal of Mining and Safety Engineering, 34(4), 689-697.

Hou, C. J., and Li, X. J. (2001). Stability principle of large and small structure of surrounding rock in fully mechanized caving roadway along goaf. Journal of China Coal Society, 26(1), 1-6.

Jiang, L., Sainoki, A., Mitri, H. S., Ma, N., Liu, H., and Hao, Z. (2016). Influence of fracture-induced weakening on coal mine gateroad stability. International Journal of Rock Mechanics and Mining Sciences, 88, 307-317.

Jiang, L., Zhang, P., Chen, L., Hao, Z., Sainoki, A., Mitri, H. S., and Wang, Q. (2017). Numerical approach for goaf-side entry layout and yield pillar design in fractured ground conditions. Rock Mechanics and Rock Engineering, 50, 3049-3071.

Le, Q. P., Dung, T. L., Thang, D. P., and Tuan, A. N. (2019). Strata movement when extracting thick and gently inclined coal seam from a physical modelling analysis: a case study of Khe Cham basin, Vietnam. Sustainable development of mountain territories, 11(4), 561-567.

Le, P. Q., and Van T. D. (2021). Research on the stability of reused roadways at Khe Cham I coal mine. Journal of Mining and Earth Sciences, Vol, 62(5a), 94-102. (in Vietnamese).

Liu, X., Xu, H., Li, B., He, W., Liang, X., and Xia, H. (2023). Study on Surrounding Rock Failure Law of Gob-Side Entry Based on the Second Invariant of Deviatoric Stress. Sustainability, 15(13), 10569.

Mohammadi, H., Ebrahimi Farsangi, M. A., Jalalifar, H., and Ahmadi, A. R. (2016). A geometric computational model for calculation of longwall face effect on gate roadways. Rock Mechanics and Rock Engineering, 49, 303-314.

Morozov, K., Shabarov, A., Kuranov, A., Belyakov, N., Zuyev, B., Vlasenko, D., ... and Bakhtin, E. (2019). Geodynamic monitoring and its maintenance using modeling by numerical and similar materials methods. In E3S Web of Conferences. 1st International Scientific Conference “Problems in Geomechanics of Highly Compressed Rock and Rock Massifs”. 129, 12 papers. e3sconf/201912901012.

Pang, D., Niu, X., He, K., Li, C., Pang, D., Hu, T., ... and Luo, X. (2022). Study on the Deformation

Mechanism of the Bottom Plate along the Empty Lane of Deep Mining and the Control Technology of the Bottom Drum. Geofluids, 2022, Article ID 3429063, 16 pages

Shabanimashcool, M., and Li, C. C. (2013). A numerical study of stress changes in barrier pillars and a border area in a longwall coal mine. International Journal of Coal Geology, 106, 39-47.

Shabarov, A. N., Zuev, B. Y., and Krotov, N. V. (2018, May). Prospects of the physical model-based study of geomechanical processes. ISRM European Rock Mechanics Symposium - Eurock. St. Petersburg, Russia. 446958.

Shen, W. L., Bai, J. B., Li, W. F., and Wang, X. Y. (2018a). Prediction of relative displacement for entry roof with weak plane under the effect of mining abutment stress. Tunnelling and Underground Space Technology, 71, 309-317.

Shen, W., Xiao, T., Wang, M., Bai, J., and Wang, X. (2018b). Numerical modeling of entry position design: a field case. International Journal of Mining Science and Technology, 28(6), 985-990.

Shklyarsky M. F., and Zuev B. Yu. (1999). Determining the time scale in modeling slow geomechanical processes. Mining geomechanics and mine surveying: Collection of scientific works. St. Petersburg. 496 papers.

Wang, H. W., Wu, Y. P., and Xie, P. S. (2013a). Analysis of surrounding rock macro stress arch-shell of longwall face in steeply dipping seam mining. 47th U.S. Rock Mechanics/Geomechanics Symposium, San Francisco, California.

Wang, H., Jiang, Y., Zhao, Y., Zhu, J., and Liu, S. (2013b). Numerical investigation of the dynamic mechanical state of a coal pillar during longwall mining panel extraction. Rock mechanics and rock engineering, 46, 1211-1221.

Xingliang, X. U., Junsheng, L. I., Suchuan, T. I. A. N., Zhongtang, L. I. U., and Yuewen, L. I. (2016). Deformation analysis and neutral plane stability control technology of small coal pillar with gob-side entry. Journal of Mining and Safety Engineering, 33(3), 481-485.

Yang, H., Guo, Z., Chen, D., Wang, C., Zhang, F., and Du, Z. (2020). Study on reasonable roadway position of working face under strip coal pillar in rock burst mine. Shock and Vibration, 1-21.

Zhang, G., Liang, S., Tan, Y., Xie, F., Chen, S., and Jia, H. (2018). Numerical modeling for longwall pillar design: a case study from a typical longwall panel in China. Journal of Geophysics and Engineering, 15(1), 121-134.

Zhang, N., Xue, X., and Han, F. (2015a). Technical challenges and countermeasures of the co-excavation of coal and gas with no-pillar retains in deep coalmine. Journal of China Coal Society, 40(10), 2251-2259.

Zhang, Z., Bai, J., Chen, Y., and Yan, S. (2015b). An innovative approach for gob-side entry retaining in highly gassy fully-mechanized longwall top-coal caving. International Journal of Rock Mechanics and Mining Sciences, 80, 1-11.

Zubov V. P. and Le Quang Phuc (2022). Development of resource-saving technology for excavation of flat-lying coal seams with tight roof rocks (on the example of the Quang Ninh coal basin mines). Journal of Mining Institute, 257, 795–806. (in Russian).

Zuev, B. Y., Zubov, V. P., and Fedorov, A. S. (2019). Application prospects for models of equivalent materials in studies of geomechanical processes in underground mining of solid minerals. Eurasian mining, 1(8), 12.

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