关键词: 岩爆;岩性转换带;孕育机制;高地应力;微震监测;秦岭隧洞;

Abstract: For many years, the frequent occurrence of rockburst has severely restricted the construction progress of deep-buried tunnels, posing a great threat to site construction safety. The Qinling diversion tunnel of Water Diversion Project from Hangjiang River-to-Weihe River has the characteristics of high ground stress, large buried depth and complex geological structure. In order to reduce the damage caused by rockburst during the excavation process, the microseismic monitoring technology was used to carry out all-weather and uninterrupted monitoring in the northern TBM section of Qinling Tunnel. By analyzing the spatial-temporal evolution process of microseismic events, the mechanism of rockburst occurred in the lithologic transformation zone at the interface between metasandstone and diorite (from mileages K46 + 735 m to K45 + 730 m) was investigated. The results show that: ① the spatial-temporal evolution law of microseismic events can effectively reveal the failure process of rock mass in rockburst area, and the changes of the microseismic monitoring source parameters were consistent with the rockburst phenomenon occurring in the field. ② Under the influence of excavation disturbance, the rock mass in the rockburst area suffered from static failure under high stress, while the slip dislocation of the structural plane produced high stress. The superposition of the static stress in rockburst area and dynamic stress generated by slip of the structural plane finally induced intense rockburst. The research results can provide a reference for the formulation of rockburst prevention measures during the construction of deep-buried tunnels, so as to ensure the safety of construction personnel and equipment on site.

Key words: rockburst; lithologic transformation zone; formation mechanism; high stress; microseismic monitoring; Qinling Tunnel