Rockburst disasters in coal mine

摘要

The ruckburst of granite from Kailuan coal mine was reproduced by a new triaxial experimental system. The experimental results show that the rockburst process can be divided into four stages including calm period, grain ejection, sheet cracking and entire collapse. The rockburst intensity is classified by the ratio of maximum principal stress to uniaxial compressive strength. Three types of rockburst for the granite have been defined as delayed rockburst, normal rockburst, and instantaneous rockburst, according to the duration from suddenly unloading to rockburst occurring. Primary mechanism for the granite was studied.