Study on Coal Pillar Width and Surrounding Rock Control of Gob-Side Entry in Extra-thick Coal Seam
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ORIGINAL PAPER
Study on Coal Pillar Width and Surrounding Rock Control of Gob-Side Entry in Extra-thick Coal Seam Xiaobin Li
. Yongqiang Zhao . Wenrui He . Liang Li . Fulian He
Received: 30 April 2020 / Accepted: 12 July 2020 Ó Springer Nature Switzerland AG 2020
Abstract This paper adopts an integrated method of field test and numerical simulation to study coal pillar width and surrounding rock control of gob-side entry in extra-thick coal seam. Field test showed that when the coal pillar width was 30 m, the average plastic failure areas of the roof, coal pillar rib and virgin coal rib were 7.6 m, 4.9 and 3.8 m, respectively, and severe roof subsidence and large deformation of coal pillar rib occurred during the mining of the working face. A numerical model is established to study the change of plastic bearing zone and the distribution of stress and displacement under different pillar widths. The numerical results show that a coal pillar 8 m wide can meet the strength requirement of overlying load and puts the gob-side entry in a good stress environment. Finally, an optimal coal pillar width was estimated at 8 m and an effective support method was proposed. Drilling imaging data indicate that the newly designed pillar size and the proposed supporting method can ensure roadway stability. The proposed plastic bearing zone and zero-displacement plane are reliable indicators for designing pillar size. In addition, the new support strategy can be applied to other coal mines with similar geological conditions.
X. Li (&) Y. Zhao W. He L. Li F. He School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China e-mail: [email protected]
Keywords Coal pillar Support method Gob-side entry Numerical simulation Extra-thick coal seam
1 Introduction At present, with the development of fully mechanized top-coal caving technology and large-scale mining equipment, the mining of extra-thick seams with a thickness of 12–15 m or more has become an important development direction in China (Wang et al. 2015; Si et al. 2015; Guo et al. 2017). The mining of extra-thick coal seam is often confronted with surrounding rock control problems such as large crosssection, strong mining and thick top coal (Guo et al. 2018a, b; Zhang 2019). In addition, the construction and development of resource-saving mines make the width of coal pillar smaller (Yuan et al. 2019). Especially under the condition of narrow coal pillar, the difficulty of surrounding rock control is greatly increased, and the traditional control technology is difficult to realize the support of narrow coal pillar gob-side entry (Jena et al. 2019; Huang and Cao 2019; Guo et al. 2018a, b). Therefore, it is necessary to carry out further research on pillar width and surrounding rock control of gob-side entry in extra-thick coal seam. In recent years, some researchers have also carried out relevant research and exploration on coal pillar. Based on a double-yield mode
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