80 / 2023-06-11 07:18:57

coal bump prevention methods with its classification and mechanics

coal bump,mechanics

Coal bump seriously threatens the safety and economy of coal mining. The causality mechanism research of coal bump is of great significance. Based on the phenomena of coal bump occurred in roadway, workface and other sites, this paper classify coal bumps to two types, one is part bump, anther is entirety bump. Their mechanisms are compressing-shearing and unloading- slipping. The former is very common and most researchers focus on this. The coal bump is from static fracture to dynamic instability. Coal mechanics property and its loading play important roles on it. The later is less common and just few researchers pay attention to it. Based on the elastic foundation theory, the upward deflection characteristics of the front and lateral roof of the working face under the condition of hard roof are analyzed, and compared with the engineering practice of roof rebounding. By analyzing the relationship between horizontal stress of coal mass, friction force of coal-roof and coal-floor and tensile resistance of coal mass, the critical equilibrium equation of coal bump is established. It is proposed that, the vertical pressure of coal seam is reduced due to the upward deflection of roof, the underneath coal mass loses its clamping forces and is removed into the roadway after overcoming the friction between roof and floor and the tensile strength of coal mass under the action of horizontal stress, that is, the unloading and slippage mechanism of coal bump in hard roof mining roadway.