Study of An Innovative Approach of Roof Presplitting for Gob-Side Entry Retaining in Longwall Coal Mining

Xingyu Zhang, Liang Chen, Yubing Gao, Jinzhu Hu, Jun Yang and Manchao He
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Xingyu Zhang: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Beijing 100083, China
Liang Chen: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Xuzhou 221116, China
Yubing Gao: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Beijing 100083, China
Jinzhu Hu: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Beijing 100083, China
Jun Yang: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Beijing 100083, China
Manchao He: State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Beijing 100083, China

Energies, 2019, vol. 12, issue 17, 1-16

Abstract: Gob-side entry retaining (GER) is a hot issue with regard to saving resources and reducing the drivage ratio in longwall mining. This paper investigates an innovative approach of roof presplitting for gob-side entry retaining (RPGER). RPGER uses the directional cumulative blasting to split the roof in advance. The rock roof within the presplitting range caves in gob after mining. The caved gangue can become the natural rib of the gob-side entry and expands to be the natural supporting body for resisting the upper roof movement. A numerical model of RPGER was established by the discrete element method (DEM), which showed that the supporting effect by the expanded gangue was well functioning. The gob-side entry was in pressure-relief surroundings and featured in the lesser deformation. The roof presplitting design method was presented and validated with a field test. The test illustrated that RPGER reduced the mining pressure on the retained entry side. The expanded gangue on the entry side was gradually compacted. It is the compaction process that played the role of reliving mining pressure, and the compacted gangue became the effective rib of the gob-side entry. The retained entry in the pressure-relief surroundings would stabilize a lagging distance behind the working face. The gob-side entry after stabilization met the entry retaining and the safety production requirements. This work illustrates the mechanism of RPGER and validates its feasibility and efficiency.

Keywords: roof presplitting; gob-side entry retaining; retaining mechanism; numerical simulation; field test (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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