Mechanism of rock burst in rectangular section roadway

The critical plastic softening zone depth and the critical load of rock bursts in a rectangular section tunnel are obtained based on the roof shear beam model for rock burst problem of roadway, and the effects of correlation factors on the critical conditions are investigated. The results show that the damage of roof rock strata is dominated by the shear deformation, and the critical depth and the critical load of the plastic zone are important parameters for identifying risk impact. Rock burst will easily happen if the critical depth and the critical load of the plastic zone are small. Its occurrence frequency is higher, but its intensity is smaller, and the destruction is also small. When they are large enough, the opposite situations occur. The influence factors of rectangular section in roadways include roadway width, height or thickness of coal seam, thickness of roof, stiffness ratio of coal seam and roof, modulus, intensity parameter, lateral pressure coefficient and horizontal stress distribution index. The critical depth of the plastic zone increases a little with the height-width ratio of roadway, and it increases with the increase of the thickness of the roof, stiffness ratio and horizontal stress distribution index. It decreases with the increasing plastic stiffness softening, internal friction angle and lateral pressure coefficient, and it has nothing to do with the initial magnitude of the cohesive force. The critical load decreases with the height-width ratio of roadway and it increases with the increase of the thickness of the roof, stiffness ratio, modulus ratio, cohesive force, internal friction angle and lateral pressure coefficient. It decreasess with the increasing plastic stiffness softening and horizontal stress distribution index.