Study on failure mode of surrounding rock in longwall face of steep coal seam

Abstract

Taking a mine in Xinjiang as the engineering background, and with the help of an bottom friction test and FLAC3D software, the pseudo-inclined coal seam is systematically analyzed. The movement and failure modes of the coal wall and roof and floor of the inclined longwall face are defined and solved with reference to the Ferrenius method, and the stability coefficient of the coal body is solved. The research shows that the coal body in the upper and middle areas of the working face is the first to break, which is prone to coal wall spalling and floor slippage. It forms a strong impact on coal gangue remaining in the lower face and goaf along different trajectories. In the production practice, the stability of the coal body can be controlled by adjusting the influencing factors such as the gravity of the coal body, the pressure of the top plate, the supporting force of the bottom plate, the length of the broken surface of the coal body, and the cohesive force, combined with diamond-shaped metal mesh and high-strength anchors to strengthen the bottom plate and “brown rope + annular grouting pipe + slurry” flexible reinforcement of coal walls and other technologies, safe and efficient mining in steeply inclined coal seam long-wall face can be realized.

Keywords

• pseudo-incline working face
• longwall mining
• ferrenius method
• coalwall failure
• movement of surrounding rocks