Strength Weakening Mechanism of Rockbursts and Its Practice

摘要

Force catastrophe of coal and rock includes coal and gas outburst and rock burst. Its essential is self-organizing critical process of energy accumulation and dissipation. When the elastic energy accumulated in coal and rock mass reaches the critical burst energy, the coal mass will be burst failure, and rock burst will be induced. According to experimental researches, elastic and brittle coal mass is the main-body of energy accumulation and dissipation, key roof stratum, especially the movement of the hard thick sandstone roof can cause accumulation and dissipation of energy in coal mass to lose dynamic equilibrium with higher speed. Breeding process of rock burst should be followed: Movement of main key roof stratum→accumulation and dissipation of energy in coal mass losing dynamic equilibrium→rock burst. As the foundation of the positive relation between bursting liability of combined samples and strength and thickness of its roof, according to the theory of energy accumulation and dissipation, this paper puts forward the strength weakening mechanism of coal and rock force catastrophe, that is to say, the strength of coal and rock mass can be weakened through unload with borehole and deep hole relieving shot, so the ability of energy accumulation will be reduced, and A large amount of elastic energy accumulated in coal and rock mass will be released, which will can make it sure that the elastic energy accumulated in coal and rock mass would not exceed the minimum energy induced rock burst. At the same time, the effect of the strength weakening can be checked with Electromagnetic Radiation (EMR) instrument, in the end, the aim of eliminating or reducing the danger of rock burst can be achieved. The validity of this kind of mechanism has been fully proofed by the production practice of 9202 high danger work face in Sanhejian Coal Mine (SCM) of Xuzhou Mines Group.