Abstract: To analyze the formation mechanism of slabbing thin plate in surrounding rock and the mechanical mechanism of bulking rock burst, the differentiation law of principle stresses during the deep roadway excavation was studied by numerical simulation. Based on three-parameter viscoelasticity constitutive relationship and the slabbing thin plate mechanical model for buckling rock burst, the buckling time-dependency equation of buckling rock burst under two dimensional stress state was theoretically derived, and the time-dependency features of bulking rock burst under different stress states were discussed. Simulated results indicate that for the roadway where vertical geo-stress is greater than horizontal geo-stress, the principle stresses decrease and the rock energy releases gradually in the roof and floor with the excavation process, while the principle stresses in sidewalls appear to be largely different, the tangential stress increases while the axial stress decreases in sidewalls where the rock mass energy accumulates massively. On the contrary, for the roadway where horizontal geo-stress is greater than vertical geo-stress, the differentiation evolution process of stresses and the characteristics of energy accumulationare the opposite. The results illustrate the mechanism of delayed rock burst, that is, when the slabbing thin plate structure in surrounding rock forms, the thin plate starts to bend and creep under the action of two-dimensional stress state, after the deformations reach to a limited value in a period of time, the slabbing thin plate structure will bulking fail and release massive elastic strain energy simultaneously.

Key words: buckling rock burst, stress differentiation, slabbing plate structure, time delayed effect, bending creep