Analysis of coal pillar width and stability control of gob-side entry driving in deep island coal face

Gob-side Entry Driving in coal mines could greatly improve the coal recovery rate, compared with traditional roadways with large coal pillars. However, the deformation of Gob-side Entry Driving is usually large and it becomes more difficult to control the stability, especially in deep coal mines. Based on the stability problems of the roadway in the first island coal face, 800 m underground in Guqiao Coal Mine in Huainan mining area, the numerical simulation model is established by FLAC to analyze the distribution of stress and displacements of the surrounding rock of Gob-side Entry Driving with coal pillar of different widths and support schemes during the excavation. The results obtained from numerical simulation and engineering practice indicated that the 8 m wide coal pillar was relatively reasonable. The support schemes including high strength and pre-stressed thread steel bolt support system combined with pre-stressed anchor cable beam and grouting in the narrow pillar is carried out to control the stability of Gob-side Entry Driving in deep island coal face under overlying mining pressure. Field measurements indicate that the deformations of surrounding rock could be controlled efficiently in 31 days after the bolt support schemes were implemented in the roadway excavated with 8 m wide narrow pillar along the adjacent goaf side 10 months after the mining of coal face nearby was finished, and the mining influence range of overlying coal face on the stability of Gob-side Entry Driving is the area from 50 m ahead of the coal face to 70 m after the coal face passing the measurement point. The results provide valuable practical guidance for the stability control of Gob-side Entry Driving in deep coal mines.