Conception for strata control and intelligent mining technology in deep coal mines with depth more than 1 000 m

Deep resource development is an important area for Chinese future scientific and technological research and development. In this paper,the current status of strata control and intelligent mining technology for coal mines with a depth more than 1 000 m is evaluated. With the focuses on the theme of safe and efficient mining activity,taking into consideration of the interaction between entry excavation and coal extraction,some key scientific issues and technique conceptions are proposed aiming to increase the length of longwall face,achieve intensive production,reduce the rate of excavation,and increase coal recovery rate. There are four key scientific issues:1) the large-deformation mechanism of roadways with a depth 1 000 m and above;2) the cooperative control principle of “ bolting-grouting-destressing” for the rock surrounding a roadway;3) the evolution mechanism of stresses and overlying structure of 350 m extra-long longwall face;and 4) multi-information integration intelligent mining mode for extra-long longwall face. These key sci- entific issues will provide a theoretical basis for strata control and intelligent mining in deep coal mines. Based on the characteristics of high in-situ stresses and strong mining induced stresses suffered by coal mine roadways at 1 000 m deep and above,a cooperative control technology called “bolting-grouting-destressing” is proposed to achieve an active support by means of a combination of rock bolts with high prestressed,high strength,and high impact toughness,high- pressure split grouting and modification of broken rock mass,and active destressing using hydraulic fracturing. It is ex- pected that this trinity technology can solve the problem of strata control for coal mine roadways at 1 000 m deep and above. Based on the characteristics of partition breaking of overlying strata and dynamic migration of ground pressures during coal mining process in extra-long longwall face at 1 000 m depth, the anti-impact technology for hydraulic shields is developed. The self-adaptation group cooperative control technology and equipment with multi-information in- tegration anti-impact hydraulic shields,and systematically integrating shearer and other equipments used in longwall face. In this way,a complete technology system of intelligent mining will be formed for extra-long longwall face at 1 000 m depth,aiming to provide theoretical and technical supports for the safe,efficient and high-recovery mining of deep coal resources.