Geomechanical types and mechanical analyses of rockbursts

- A grading scheme of rockbursts was proposed.
- Six geomechanical types of rockbursts were proposed and classified into two major types.
- The occurrence criteria of the stress rockbursts were analyzed via fracture mechanical theories.
- The occurrence criteria of the stress-structure rockbursts were analyzed via catastrophe theories.

Rockbursts generally occur in highly stressed rock masses because of underground openings. To ensure the safety of construction works, factors that play a role in predicting and preventing rockbursts should be analyzed. Based on numerous geological and mechanical analyses of rockbursts in China, six basic geomechanical types of rockbursts are classified with unique developing characteristics (rock-mass structure, crack type, failure plane, energy release, etc.), which are further divided into stress rockburst and stress-structure rockburst. The stress rockbursts are characterized by the development of micro-cracks using fracture mechanical theories; the formation of a macroscopic failure plane indicates that a state of maximum energy release is achieved (along the preferred crack path). The stress-structural rockbursts are considered a structural failure when propagating cracks intersect the existing discontinuities, which are analyzed using the catastrophe models. Finally, occurrence criteria of the six geomechanical types of rockbursts are proposed.