Study On Rockburst Hazard Under Deep Large Braid Fully Mechanized Mining

According to the whole stress-strain curve of rock, coal or rock will show gradual destruction and brittle failure after the peak strength, and brittle failure will easily lead to occurrence of rockburst. Using elastic-plastic mechanics, rock mechanics and the theory of mine pressure to establish mechanical model of roof structure under deep braid mining, and to make theoretical analysis of impact failure mechanism under general stope and isolated stope, we know initial pressure and periodical pressure of basic roof under general stope will easily induce rockburst of working face, and when roof load and gob-span reach the limit state under isolated stope, rockburst of working face will easily occur. Apply the universal distinct element code UDEC3.1 to make simulation analysis of coal abutment pressure along alignment and trend of deep braid working face, acquire distribution rule of abutment pressure showing release rule of energy stored in coal and rock and make division of rockburst hazard zones. The paper makes analysis of impact hazard when reclaiming coal under deep braid mining, and divides rockbursts into roof break, coal compression and floor buckle three types against conventional working face. Impact hazard of braid working face mainly lies in the second developing stage of abutment pressure, and impact styles are mainly coal impact or roof impact; impact hazard of roadway mainly lies in roadway groove lying in superimposition area of high abutment pressure along roadway trend and working face alignment, and its impact style is coal outburst; as for isolated coal pillar, with the decrease of coal pillar size, abutment pressure distribution changes gradually from low stress bridge piece type to high stress arch type, leading to rising impact hazard. When the size of isolated coal pillar is too small, the whole coal pillar will be in plastic destruction state without impact hazard, but the whole coal pillar may lose stability. In general, large braid isolated coal pillar won't induce coal pillar rockburst in gob, and its impact hazard is mainly in roadway groove lying in superimposition area of high abutment pressure along coal pillar alignment and trend under mining influence. In addition, roadway layout in low stress zone or along space in isolated coal pillar will greatly decrease impact hazard of roadways. Finally combination with results of this paper, we make analysis and evaluation of rockburst hazard against 3107 braid working face in Liangbaosi coalmine, and put forward responding prevention and control measures, eliminating effectively impact hazard of working face, receiving excellent application effect and optimizing rockburst hazard evaluation theory and method under deep large braid comprehensive mechanized mining.