Mechanism and prevention of rock-burst induced by immediate roof breakage in shallow-buried coal seam

In order to prevent rock-burst occurring under the hard immediate roof of shallow-buried softly-inclined coal seam,micro-seismic and underground pressure monitoring equipment were used to identify the breakage location of hard immediate roof and the periodical weighting paces of basic roof. Based on the data above, rock-burst energy source and disaster-causing mechanism was analyzed,a mechanics model of immediate roof breakage was set up,the first and periodical breakage pace formula of immediate roof were deduced and the distance between breakage location and coal wall of face was calculated. The study results show that although the breakage pace and energy of immediate roof were minor than those of basic roof,the dynamic load induced by the periodical breakage of immediate roof could increase rock-burst danger in mining face. Therefore,pre-blasting immediate roof in roadways was applied to reduce the distance between breakage location and coal wall of face and decrease rock-burst danger degree,which was demon- strated by micro-seismic monitoring data.