On the stress state in rock burst

By means of the stress state analyses on the rockmass surrounding underground openings and truely triaxial compressive testing, the stress state of rock burst and the limiting depth of rock burst in rocks are studied. The research results show that the rock burst of flake-splitting pattern takes place around the opening's surface under the biaxial compressive stress state whereas that of shearing-dislocation pattern takes place inside the rockmass. There exists a rock burst zone with a limiting depth dependent upon the ratio of the vertical principal stress to the horizontal one of the geostress field.