Cao Xiaofan, Wang Song, Wang Xiaoli, Yang Zhongyu, Li Ang
School of Architecture and Civil Engineering, Xi 'an University of Science and Technology, Xi'an, Shaanxi, China.
School of Management, Xi 'an University of Science and Technology, Xi'an, Shaanxi, China.
PLoS One. 2025 May 12;20(5):e0323337. doi: 10.1371/journal.pone.0323337. eCollection 2025.
Gob-side entry retention (GER) has been successfully advanced and implemented for several years. Notably, strong economic returns have been realised for different thicknesses of coal seams under near-horizontal and gently inclined conditions. However, implementing gob-side entry retention under the conditions of high dip angle or steeply inclined coal seam has always been difficult. This paper systematically introduces the material and construction processes of flexible formwork GER. Engineering practice, theoretical calculations and indoor test analysis were used to propose an independently designed and developed special-shaped flexible formwork concrete wall with a width of 1.2 m, a strength of C30 and an inclination angle of 20°. This wall was then used to investigate the GER technology in the No. 31342 working face of the Dachiba Coal Mine. The findings reveal that the strength of the developed coal solid waste flexible formwork concrete fulfils the design requirements, and the residual strength and healing capacity are superior to that of ordinary concrete. The design of the supporting parameters of flexible formwork GER was satisfactory in the No. 31342 working face of the Daichiba Coal Mine. The overall deformation of the roadway is small, and a decent effect is obtained with respect to retaining the roadway. Hence, the technical challenge of enacting GER in medium-thick coal seams with a high dip angle under the filling and supporting modes has been resolved successfully.
沿空留巷技术（GER）已成功推进实施多年。值得注意的是，在近水平和缓倾斜条件下，不同厚度煤层实现了可观的经济效益。然而，在大倾角或急倾斜煤层条件下实施沿空留巷一直存在困难。本文系统介绍了柔性模板沿空留巷的材料及施工工艺。通过工程实践、理论计算和室内试验分析，提出了自主设计研发的宽度为1.2 m、强度为C30、倾斜角度为20°的异形柔性模板混凝土墙。然后利用该墙体对大赤坝煤矿31342工作面的沿空留巷技术进行了研究。研究结果表明，所研制的煤矸石柔性模板混凝土强度满足设计要求，残余强度和自愈能力优于普通混凝土。大赤坝煤矿31342工作面柔性模板沿空留巷支护参数设计效果良好。巷道整体变形较小，巷道保留效果较好。因此，成功解决了在充填支护方式下大倾角中厚煤层实施沿空留巷的技术难题。
