Improving stress environment in development entries through an alternate longwall mining layout
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ORIGINAL PAPER
Improving stress environment in development entries through an alternate longwall mining layout Pengfei Wang 1 & Jingli Zhao 2,3 & Guorui Feng 1,4 & Zhiqiang Wang 2 Received: 16 March 2017 / Accepted: 26 December 2017 / Published online: 19 January 2018 # Saudi Society for Geosciences 2018
Abstract Most coal mines in China use the longwall mining system. High stresses are frequently encountered around development entries at deep mines. This paper presents an alternate longwall mining layout for thick coal seams to minimize ground control problems. In a conventional longwall panel layout, development entries on both ends of the panel are located along the floor, and a coal pillar (chain pillar) is left between adjacent panels to ensure stability. Gateroads on either end of a longwall panel using the layout proposed in this paper are located at different vertical levels within a thick coal seam or in a geologically split coal seam for improved stability. The headgate entry/ies are driven along the floor while the tailgate entry/ies are driven along the roof. Therefore, a longwall face has a gradually elevated or curved section on one end of the panel. For the adjacent panel, the development entry may be located directly below the development entry of the previous panel or may be offset horizontally with respect to it. Based on physical and numerical modeling approaches, it is demonstrated that the stress environment for development entries employing the longwall layout is significantly improved; ground control problems are therefore minimized. Keywords Longwall mining . Stress environment . Curved section . Numerical modeling . Tailgate entries
Introduction Coal currently plays a dominant role as China’s energy resource, and it is expected to remain so in the next five decades. Since easily minable deposits are getting depleted, reserves under difficult conditions must be mined to meet societal needs. Many coal mines in Shandong province, PR China, are mining at depths of more than 800 m, which have very high ground pressures that can lead to ground control problems in longwall mining (Xie and Zhou 2012).
* Guorui Feng [email protected] 1
College of Mining Engineering, Taiyuan University of Technology, No. 79, Yingze Western Avenue, Taiyuan, Shanxi 030024, China
2
College of Resource and Safety Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
3
Russian Academy of Natural Sciences, Moscow 119991, Russia
4
Shanxi Engineering Research Center for Green Mining, Taiyuan 030024, China
In China, the principal mining method of underground coal extraction is single-cut retreat longwall mining. The stability of development entries or gateroads plays a significant role in safe and productive longwalls. A failure or collapse on gateroads can lead to accidents and/or interruption of mining operations with significant economic loss (Shen et al. 2008). Gateroads and chain pillars between longwall mining panels are subjected to a complex dynamic loading process during th
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