Analytical study to estimate rib spalling extent and support requirements in thick seam mining
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ORIGINAL PAPER
Analytical study to estimate rib spalling extent and support requirements in thick seam mining Wei-bin Guo 1 & Chang-you Liu 2 & Guo-wei Dong 3 & Wen-yu Lv 3 Received: 9 December 2017 / Accepted: 28 March 2019 # Saudi Society for Geosciences 2019
Abstract In order to better understand the mechanism behind the poor stability of support and surrounding rocks at mechanized working faces with increased mining height (MWMH), a conceptual model of the support and rocks surrounding the MWMH, under different structural conditions of the main roof, is established in this study. On the basis of the mechanical model, the interaction among the coal wall, support and roof in MWMH is studied. The analytical analysis reveals that the coal wall and support interact more significantly in the MWMH than conventional approaches (e.g., conventional longwall mining). With the increase in the depth of rib spalling in coal wall, the support strength, needed to control the roof, increases linearly. While as the support strength increases, the depth of rib spalling in coal wall showed a hyperbolic-like decrease. Based on these results, the expression, which describes the relationship of the interaction between the rib spalling in coal wall and support strength in the MWMH, is proposed. Rib spalling is then controlled in real working face in a soft, thick coal seam. The field experiment demonstrates that the advanced long-hole hydrostatic pre-injection can control rib spalling in coal wall and guarantee the stability of support and surrounding rock, which enables a high-efficiency mining of the MWMH. Keywords Mechanized mining . Rib spalling . Coal wall . Rock-structure interaction . Control technique
Introduction Due to advantages including high resource recovery rate (Yuan et al. 2011a), less coal dust generated in the production of working faces, and low gas emissions (Mao and Kang 2003), mechanized mining with increased mining height (MWMH) (cutting height more than 3.5 m) has become the key technical approach used to ensure the safety and highefficiency mining of thick coal seams in China. The technique
has achieved favorable effects in coal mines in Jincheng, northern Shaanxi, and Inner Mongolia and its maximum coal cutting height can reach 7 to 8 m (Wang et al. 2016; Yan et al. 2011; Ju and Xu 2013, Sohu 2017, Meng et al. 2018). By advantage of the technique, the coal production of working face also improves; however, damage and movement of overlying strata in MWMH have significantly larger ranges and intensity, causing violent main roof impulsive loading and severe rib spalling in coal wall (Gong 2006; Ju et al. 2011;
Editorial handling: M. Karakus * Wei-bin Guo [email protected]
1
School of Energy Engineering, Key Laboratory of Western Mine Exploitation and Hazard Prevention with Ministry of Education, Safety Science and Engineering Post-Doctoral Research Station, Xi’an University of Science and Technology, Xi’an 710054, Shaanxi, China
2
School of Mines, Key Laboratory of Deep Coal Resource Mining, Minist
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