Simulation experimental investigation on rockburst of dolomite specimens at great depth tunnels

Based on the high-stress condition and the development characteristic of tectonic stress in excavating deep buried tunnels, the rockburst process of dolomite was simulated with a deep rockburst experimental system in two kinds of tectonic stress conditions:instantaneously unloading the minimum principal stress on a rectangle specimen, keeping others unchanged or maintaining the intermediate principal stress and increasing the maximum principal stress. The stress-time curve, the stress-strain curve, the acoustic emission characteristic and the rockburst law were tested. The results show that the possibility of dolomite rockburst caused by tectonic stress in the project area is striking. The critical depth of rockburst is 290 m. Rockburst caused by vertical tectonic stress shows partial sheet avalanche, belongs to lag rockburst. The intensity of rockburst caused by horizontal tectonic stress is stronger, shows massive ejection and overall fragmentation, and belongs to instantaneous rockburst. The acoustic emission (AE) peak presents in the crevice growth section, and the highest value of AE density occurs in the rock rupture segment. The maximum principal stress corresponding to the AE peak is 77.4% of that corresponding to the rock breakdown stage.