Abstract: In order to determine the bursting danger of mining zone, and to solve the limitation of coal and rock's bursting liability evaluation criterion, the stiffness values of coal’s post-peak and rock’s unloading process are used to evaluate the steady and unsteady failure of rock-coal-rock sample based on the analysis of deformation, acceleration, stiffness and energy variation. The research results indicate that rock-coal-rock sample’s failure state is determined by the contrast relation of coal’s post-peak stiffness and rock’s stiffness. There is a point S on the coal’s stress-strain curve during the unloading process where the stiffness changing ratio satisfies the relation of , after which the rock-coal-rock sample’s shall not keep the balance state, and the sample's failure will convert from stable to instable state. The parameter which is the ratio of the energy that roof and floor releases to that of coal releases is used as the index of bursting liability of rock-coal-rock sample. The results of seven sites’ samples from 2 mines indicate that there are 2 samples’ bursting liability is under the influence of roof and floor attribution. The model of rock-coal-rock sample can reflect the bursting liability of in-situ surrounding rock more accurately than that of only coal.

Key words: rock burst, bursting liability, rock-coal-rock sample, instable failure criterion