Abstract
Coal pillars are formed by excavation and mining activities in an intact coal seam and play a key role in underground coal mines. Most previous investigations of pillars have mainly focused on existing coal pillar failures. However, few scholars have investigated the failure mechanisms of coal pillars during their formation process. This paper focuses on the failure of a 7Â m-wide coal pillar that caused the large deformation of a tailgate in the Sijiazhuang coal mine in China. Field tests and numerical modeling were used to study the initiation, propagation, and failure of cracks within this gob-side coal pillar during its formation. Field monitoring revealed that the maximum roof-to-floor and rib-to-rib convergence reached 860Â mm and 1460Â mm, respectively. The coal pillar became a yield pillar with substantial fractures. A numerical model was built using UDEC Trigon logic and calibrated with laboratory tests and RQD methods. Both the natural roadway deformation and crack distribution in the coal pillar were simulated. A FISH function was used to document the propagation of shear and tensile cracks in pillars with different W/H ratios, and a damage parameter was adopted to evaluate the failure of these pillars. The results suggest that the most appropriate pillar width is 10Â m. Field trials prove that a 10Â m-wide coal pillar combined with optimized support measures can effectively control deformation around the tailgate.
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Acknowledgements
This research has been supported by the Fundamental Research Funds for the Central Universities (2017XKZD06). The authors thank Sijiazhuang coal mine for their support during the field test. Also, this article benefited from valuable comments and suggestions by co-editors and other anonymous reviewers.
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Wu, Wd., Bai, Jb., Wang, Xy. et al. Numerical Study of Failure Mechanisms and Control Techniques for a Gob-Side Yield Pillar in the Sijiazhuang Coal Mine, China. Rock Mech Rock Eng 52, 1231–1245 (2019). https://doi.org/10.1007/s00603-018-1654-3
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DOI: https://doi.org/10.1007/s00603-018-1654-3