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Energies 2017, 10(11), 1785; https://doi.org/10.3390/en10111785

An Innovative Approach for Gob-Side Entry Retaining in Thick Coal Seam Longwall Mining

1,†
,
1,2,†,* , 1,2
and
1,2
1
State Key Laboratory for 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
These authors contributed equally to this work.
*
Author to whom correspondence should be addressed.
Academic Editor: Mehrdad Massoudi
Received: 3 October 2017 / Revised: 31 October 2017 / Accepted: 2 November 2017 / Published: 6 November 2017
(This article belongs to the Special Issue Mathematical and Computational Modeling in Geothermal Engineering)

Abstract

Gob-side entry retaining (GER) is a popular non-pillar mining technique regarding how to reserve a gateroad for the use of next panel mining. When used in thick coal seams, the conventional entry retaining method requires a huge amount of filling materials and may cause entry (gateroad) accidents. Thus, an innovative non-pillar longwall mining approach is introduced. First, structural and mechanical models were built to explore the mechanism of the new approach. The modeling results indicate that effective bulking of the gob roof and reasonable support of the entry roof were key governing factors in improving entry stabilities and reducing roof deformations. Accordingly, a directional roof fracturing technique was proposed to contribute to gob roof caving, and a constant resistance and large deformation anchor (CRLDA) cable was used to stabilize the entry roof. Subsequently, the evolutionary laws of the roof structure and stresses were explored using numerical simulation. It was found that the structure of the surrounding rocks around the retained entry changed significantly after roof fracturing. The stress-bearing center was transferred to the gob area, and the entry roof was in a low stress environment after adopting the approach. Finally, the approach was tested on a thick coal seam longwall mining panel. Field monitoring indicates that the retained entry was in a stable state and the index of the retained entry met the requirement of the next mining panel. This work provides an effective and economical approach to non-pillar longwall mining in thick coal seams. View Full-Text
Keywords: coal resources; sustainable mining; gob-side entry retaining; roof fracturing; entry maintenance; surrounding rock control coal resources; sustainable mining; gob-side entry retaining; roof fracturing; entry maintenance; surrounding rock control
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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He, M.; Gao, Y.; Yang, J.; Gong, W. An Innovative Approach for Gob-Side Entry Retaining in Thick Coal Seam Longwall Mining. Energies 2017, 10, 1785.

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