Mechanism study of rock burst induced by overburden large structural action of fully-mechanized caving mining

Overburden large structure affect coal mine strata behavior,seriously it will lead to rock burst.It is necessary for studying the formation and evolution law of overburden large structure.“Plate-shell” overburden large structure model is proposed based on the critical layer theory,surrounding rock stress evolution characteristics is analyzed.Overburden large structure instability released energy equation is deduced,and rockburst critical energy is achieved under large structure.Microseismic events spatial distribution and energy variation law was researched by Microseismic monitoring methods.Study showed that combined with main roof,sub-key layer and primary key layer “Plate-shell” overburden large structure gradually evolved,vibration total energy successively stepped increased under the cover of overburden large structure,structural instability vibration total energy skipped increased.Instability of overburden large structure controlled by primary key layer can lead to rock burst.Ground pressure monitoring showed that rock stress decreasing mutation since overburden large structure instability,rising mutations due to lower part rock cycle breakage under large structure.Support load significant increasing is caused by coupling effect between dynamic load of overburden large structure instability and static load of top coal and immediate roof.