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Open AccessArticle

Analysis and Optimization of Entry Stability in Underground Longwall Mining

by Yubing Gao 1,2, Dongqiao Liu 1,2, Xingyu Zhang 1,2 and Manchao He 1,*
1
State Key Laboratory of Geomechanics & Deep Underground Engineering, China University of Mining & Technology, Beijing 100083, China
2
School of Mechanics and Civil Engineering, China University of Mining & Technology, Beijing 100083, China
*
Author to whom correspondence should be addressed.
Sustainability 2017, 9(11), 2079; https://doi.org/10.3390/su9112079
Received: 1 October 2017 / Revised: 1 November 2017 / Accepted: 10 November 2017 / Published: 12 November 2017
For sustainable utilization of limited coal resources, it is important to increase the coal recovery rate and reduce mine accidents, especially those occurring in the entry (gateroad). Entry stabilities are vital for ventilation, transportation and other essential services in underground coal mining. In the present study, a finite difference model was built to investigate stress evolutions around the entry, and true triaxial tests were carried out at the laboratory to explore entry wall stabilities under different mining conditions. The modeling and experimental results indicated that a wide coal pillar was favorable for entry stabilities, but oversize pillars caused a serious waste of coal resources. As the width of the entry wall decreased, the integrated vertical stress, induced by two adjacent mining panels, coupled with each other and experienced an increase on the entry wall, which inevitably weakened the stability of the entry. Therefore, mining with coal pillars always involves a tradeoff between economy and safety. To address this problem, an innovative non-pillar mining technique by optimizing the entry surrounding structures was proposed. Numerical simulation showed that the deformation of the entry roof decreased by approximately 66% after adopting the new approach, compared with that using the conventional mining method. Field monitoring indicated that the stress condition of the entry was significantly improved and the average roof pressure decreased by appropriately 60.33% after adopting the new technique. This work provides an economical and effective approach to achieve sustainable exploitation of underground coal resources. View Full-Text
Keywords: sustainable exploitation; coal resources; longwall mining; entry stability sustainable exploitation; coal resources; longwall mining; entry stability
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Gao, Y.; Liu, D.; Zhang, X.; He, M. Analysis and Optimization of Entry Stability in Underground Longwall Mining. Sustainability 2017, 9, 2079.

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