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Energies 2017, 10(7), 1057; doi:10.3390/en10071057

Analysis of Overlying Strata Movement and Behaviors in Caving and Solid Backfilling Mixed Coal Mining

1
State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China University of Mining & Technology, Xuzhou 221116, China
2
Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, School of Mines, China University of Mining and Technology, Xuzhou 221116, China
3
Faculty of Transportation Engineering, Huaiyin Institute of Technology, Xuzhou 221116, China
*
Author to whom correspondence should be addressed.
Received: 27 May 2017 / Revised: 6 July 2017 / Accepted: 11 July 2017 / Published: 21 July 2017
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Abstract

Based on techniques of close upper protective coal-rock layer mining, relieved gas extraction, and underground gangue washing-discharging-backfilling, this paper initiates the concept of mixed fully-mechanized coal mining, which combines a solid backfilling method and a caving method (hereinafter referred to as “backfill and caving mixed mining”). After the principle and key techniques are introduced, a physical simulation experiment and a numerical simulation are used to study the characteristics of the overlying strata’s fracture development, the main roof subsidence, the stress field and its influence area in the transition area with the length ratios of the backfilling section and the caving section, and the advancing distance of the mixed longwall face. Thus, the lengths of the caving section and the backfilling section, the parameters of the support system in the transition section, and the design process of the mixed longwall face are presented. In practice, the mixed longwall face Ji15-31010 in Ping-dingshan No. 12 Colliery proves that the designed lengths of 120 m and 100 m for the backfilling section and the caving section, respectively, are appropriate. The monitoring results of the hydraulic support working resistance show that the supports were working well in general; the maximum growth height of the overlying strata fracture is 18 m; the gas drainage efficiency is up to 80% and the average gas concentration is 0.1 g/m3; a large quantity of gangue generated in the Ji14 seam is disposed underground; coal and gas are extracted simultaneously; and significant environmental and economic benefits are realized. View Full-Text
Keywords: mixed coal mining; strata movement and behavior; fractures development; transition section; backfilling section; caving section mixed coal mining; strata movement and behavior; fractures development; transition section; backfilling section; caving section
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Huang, Y.; Zhang, J.; Yin, W.; Sun, Q. Analysis of Overlying Strata Movement and Behaviors in Caving and Solid Backfilling Mixed Coal Mining. Energies 2017, 10, 1057.

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