Abstract
With the characteristic of less roadway excavation and high resource recovery, gob-side entry retaining (GER) technology is a safe and efficient green mining technology. Many experts and scholars have done extensive research on its principle and application. However, GERs are rarely used in thick soft coal seams. In this paper, based on the geological conditions of a coal mine in China, we propose a novelty approach of GER in thick three-soft coal seam (it means a single seam with a soft roof and a soft floor). The engineering scheme includes roadway expansion, large section roadway support, cutting roof to relieve pressure, and road-inside backfill body construction. The established mechanical and numerical calculation models effectively guide the engineering practice. Field observations showed that all the processes met the requirements of field production. The research results could provide theoretical guidance for the application of GER under similar geological conditions.
Highlights
China’s coal production ranks first in the world, accounting for 51% of the world’s total coal output in 2020 and accounting for more than 57% of the country’s primary energy consumption
20–50 m wide coal pillars are allowed to remain between longwall panels to reduce the impact of mine-induced stress (Figure 1(a))
With the development of theoretical research on underground support for stopes, procedures for gob-side entry driving with narrow coal pillars have been developed (Figure 1(b))
Summary
China’s coal production ranks first in the world, accounting for 51% of the world’s total coal output in 2020 and accounting for more than 57% of the country’s primary energy consumption. With the development of theoretical research on underground support for stopes, procedures for gob-side entry driving with narrow coal pillars have been developed (Figure 1(b)). Gob-side entry driving significantly improves coal recovery; the narrow coal pillars may be damaged by mining pressure resulting in air leakage into the goaf [4]. This can lead to spontaneous combustion or other mine disaster accidents [5, 6]. Investigators in Germany developed low-water material mainly composed of gypsum, fly ash, cement, and gangue that they used to fill one side of a gob-side entry The engineers in the former Soviet Union designed a variety of supports for gob-side entry. If no remedial measures are employed, the GER may not succeed
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