To further investigate the influence of surrounding rock mass damage on the rock burst mechanism, material selection for simulating the damage zone was carried out, and a test piece containing the damage zone (1000 mm×600 mm×400 mm) was fabricated. Using the self-developed rock burst model test system's drilling device, caverns were excavated in the specimens (with a hole diameter of 110 mm). Rock burst model tests were then conducted on specimens with varying damage zone thickness through step loading, considering the damage effects on the surrounding rock. During the tests, cameras monitored the damage process of the tunnel wall. Image expansion was performed based on the rubber paper model principle, and the box dimension of the expanded image was calculated and analyzed. The results show that the macro-failure process of a rock burst consists of crack initiation, particle ejection, crack propagation, and debris avalanche stages. As the thickness of the damage zone increases, the failure depth of the specimen chamber's side wall gradually increases. In the stage of slow increase and sharp increase in the box dimension of the left and right tunnel walls, the growth rate of the box dimension decreases linearly with the increasing thickness of the damage zone. With the increase in damaged zone thickness, cracks in the tunnel wall primarily concentrate within the damaged zone during loading, and the damage depth of the tunnel wall increases when the cavity is damaged. The findings further elucidate the breeding and failure mechanism of rock bursts in deep-buried caverns under the condition of surrounding rock damage.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |