Study on the Influence of the Location of Dirt Band on Top Coal Caving Property in Extra-Thick Coal Seam
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ORIGINAL PAPER
Study on the Influence of the Location of Dirt Band on Top Coal Caving Property in Extra-Thick Coal Seam Chaowen Hu
. Wei Liu . Yongtao Wang
Received: 21 April 2020 / Accepted: 18 June 2020 Ó Springer Nature Switzerland AG 2020
Abstract The influence of dirt band on the top coal caving property is usually analyzed from the thickness and hardness of the dirt band. For the extra-thick coal seam with a thickness of more than 20 m, the location of the dirt band also has a huge impact on the top coal caving property. In this paper, No. 19 coal seam of Tanyaoyu coal mine is took as the research object, the influence of the location of dirt band on the top coal caving property is analyzed, and the calculation formula of the limit span and thickness of the dirt band is derived. The results show that, when the dirt band located in the upper part of the extra-thick coal seam, the bridge structure is more to form in the mining process, when the dirt band located in the middle part of the extra-thick coal seam, the arch structure is more to form, when the dirt band located in the lower part of the extra-thick coal seam, the dirt band is to release in the form of a loose media. The upper dirt band and lower dirt band have little influence on the top coal caving property, while the middle part dirt band has the greatest influence on the top coal caving property. Keywords Extra-thick coal seam Dirt band Top coal caving property Numerical simulation
C. Hu (&) W. Liu Y. Wang Transportation Institute, Inner Mongolia University, Hohhot 010070, Inner Mongolia, China e-mail: [email protected]
1 Introduction Generally, the coal seam with a thickness of more than 8 m is defined as extra-thick coal seam (Fan et al. 2020; Deng et al. 2016; Zhou et al. 2019). With the development of coal mining technology and equipment, the theory and technology of extra-thick coal seam mining had great progress. In March 2018, Shangwan Coal Mine of Shendong Coal Group successfully tested extra-large working-face in 8.8 m, and creating several world records. In Shanxi, Inner Mongolia, Shaanxi and other areas in China, extrathick coal seams with a thickness of more than 20 m are common (Yang et al. 2019a, b). At present, for extra-thick coal seams with a thickness of more than 20 m, only slice mining or top coal caving technology can be used (Baryshnikov et al. 2002; Shahani et al. 2020; Islam et al. 2009). However, the greater thickness of the coal seam, the more obvious disadvantages of slice mining prominent, such as more unit yield, more cost, more labor intensity of workers, more to cause the tension of mining and development replacement (Howladar et al. 2014; Islam et al. 2009; Le et al. 2017). For fully mechanized sublevel caving technology, as long as the recovery rate can be improved, it can give full play to the technical advantages, such as low unit yield, low cost, low labor intensity of workers, easy to mining and development replacement, etc. The good caving property
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