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Open AccessArticle

Key Parameters of Gob-Side Entry Retaining in A Gassy and Thin Coal Seam with Hard Roof

by Shuai Yan 1,2, Tianxiao Liu 1,2, Jianbiao Bai 1,2,* and Wenda Wu 1,2
1
Key Laboratory of Deep Coal Resource Mining (CUMT), Ministry of Education, Xuzhou 221116, China
2
School of Mines, China University of Mining & Technology, Xuzhou 221116, China
*
Author to whom correspondence should be addressed.
Processes 2018, 6(5), 51; https://doi.org/10.3390/pr6050051
Received: 4 April 2018 / Revised: 3 May 2018 / Accepted: 3 May 2018 / Published: 7 May 2018
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
Gob-side entry retaining (GER) employed in a thin coal seam (TCS) can increase economic benefits and coal recovery, as well as mitigate gas concentration in the gob. In accordance with the caving style of a limestone roof, the gas concentration and air pressure in the gob were analyzed, and a roof-cutting mechanical model of GER with a roadside backfill body (RBB) was proposed, to determine the key parameters of the GER-TCS, including the roof-cutting resistance and the width of the RBB. The results show that if the immediate roof height is greater than the seam height, the roof-cutting resistance and width of the RBB should meet the requirement of the immediate roof being totally cut along the gob, for which the optimal roof-cutting resistance and width of RBB were determined by analytical and numerical methods. The greater the RBB width, the greater its roof-cutting resistance. The relationship between the supporting strength of the RBB and the width of the RBB can be derived as a composite curve. The floor heave of GER increases with increasing RBB width. When the width of the RBB increased from 0.8 m to 1.2 m, the floor heave increased two-fold to 146.2 mm. GER was applied in a TCS with a limestone roof of 5 m thickness; the field-measured data verified the conclusions of the numerical model. View Full-Text
Keywords: gas concentration; gob-side entry retaining (GER); limestone roof; roof-cutting resistance; roadside backfill body (RBB) gas concentration; gob-side entry retaining (GER); limestone roof; roof-cutting resistance; roadside backfill body (RBB)
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Yan, S.; Liu, T.; Bai, J.; Wu, W. Key Parameters of Gob-Side Entry Retaining in A Gassy and Thin Coal Seam with Hard Roof. Processes 2018, 6, 51.

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