Stability Analysis of Surrounding Rock in the Diversion Tunnel at the Xulong Hydropower Station based on RFPA3D and Microseismic Monitoring

To study the surrounding rock stability of excavated geologically weak section #2 diversion tunnel in Xulong Hydropower Station, a quasi-3D numerical model was built using Realistic Failure Process Analysis (RFPA3D) system to simulate damage and failure process consisting crack initiation, growth, penetration mass after excavation, reveal instability mechanism inside mass. Moreover, microseismic monitoring technology employed delineate potential danger areas explore possible modes. Results indicate that profile failed as different degrees during excavation process, most obviously near vault corners side wall, where tensile predominated. As proceeded, events increased gradually at energy from acoustic emissions accumulated steadily, thus raising possibility collapse bursts this area. The research results can provide technical support for construction project Station serve guide similar underground projects.