Technology of pressure relief by roof cutting for directional-predetermined crack blasting in gob-side entry retaining in Guhanshan Mine

The pressure arch in overburden during coal mining usually has an adverse effect on gob-side entry retaining. This paper proposed a method to reduce the adverse effects of pressure arch for No. 17021 mining face of Guhanshan coal mine. Based on the geological conditions of the No. 17021 mining face, technology of pressure relief by roof cutting in gob-side entry retaining was improved. The new technology combined the technology of front reinforcement support, directional-predetermined crack blasting, and reinforcement of gob side entry retaining. The implementation scheme was then conducted and applied in the haulage gateway. This scheme contained parameters of directional cutting seam blasting and support methods and its parameters of the front roadway and gob-side entry. The specification of gob-side entry was evaluated through mine pressure measurements. The results showed that average subsidence of the gob-side entry was 248 mm, the average displacement at the two sides was 350 mm, and the average support resistance was 37 MPa, which indicated a satisfaction of the usage requirement for gob-side entry.