Mechanism of rockburst under stress wave in mining space

Aiming at the problem of occurrence and evolution of large-scale rockburst under dynamic impact,the gen- eration mechanism of dynamic stress wave in mining space was analyzed,the law of impact failure of coal under the coupling of dynamic stress wave and static load was studied,and the evolution mechanism of large-scale rockburst was finally interpreted from the perspective of the generation,propagation,and impact of dynamic stress wave. The results show that the amplitude of the dynamic stress waves generated by hard roof fall and coal fracture in stress concentra- tion zone increases with the coal and rock strength,and the duration of the stress wave increases with the fracture scale,which indicates that coal and rock with higher strength fracture in large scale would cause stronger dynamic stress wave in underground coal mining. The results of coupling loading experiments of dynamic stress wave and static stress show that high static stress,high dynamic stress wave,or the coupling of static stress and dynamic stress wave all could result in impact failure of coal,and the required critical dynamic stress wave first increases and then decreases with the increment of static stress,and the turning point is about 50% of the uniaxial compressive strength of coal. When the static stress reaches the critical point,the required dynamic stress wave decreases significantly,which indi- cates that the coal and rock mass under high geo-stress condition is more significantly affected by the dynamic stress wave. The results of large-scale simulation show that the failure area of coal mass under dynamic stress wave increases gradually and concentrates on both sides of the roadway,and the failure area increases with the increment of amplitude and duration of dynamic stress wave. The mechanism of rockburst under stress wave was finally proposed,which dem- onstrates that the rockburst under dynamic impact is resulted by the coupling of static stress,dynamic stress wave and the coal-rock structure,the large-scale fracture of the coal and rock in mining space generates strong dynamic stress wave,then the coupling of static geo-stress and dynamic stress wave causes a large-scale failure of surrounding rock, thereby results in a rockburst.