Conceptual models for rock burst and energy transformations in strain burst

Abstract

The occurrence of a rock burst event depends on two requisites: the secondary stresses after rock excavation must be beyond the rock strength and there are excessive energy releases from the rock mass in addition to the energy release for rock fracturing. These two requisites are first illustrated in a general ball-cliff conceptual model for rock burst in the paper. After that, three specific conceptual models are deduced from the general model for strain burst, seismic strain burst and seismic burst. The excessive energies for rock burst are released from both the burst rock itself and from the surrounding rock mass. The proportions of the two energy portions are associated with the burst depth. When the burst is shallow, the burst energy is dominated by the portion from the burst rock itself, but the weight of the energy contribution from the surrounding rock mass increases with an increase in the burst depth. The dependence of the proportions of these portions of energy releases on the burst depth is demonstrated through an analytical study of a circular tunnel that is subjected to rock burst.