Investigation on Characteristics and Prevention of Rockburst in a Deep Hard and Soft Compound Stratum Tunnel Excavated Using TBM

Rockburst disasters frequently occur in deep tunnels excavated by TBM (tunnel boring machine) under complex geological conditions western China. Using FLAC3D, the characterization of a three-dimensional numerical model compound stratum tunnel is conducted, based on water transport project Shanxi Province. Then, characteristics rockburst hard and soft are revealed, energy criteria considering rock brittleness proposed. In addition, prevention control method drilling pressure relief for has been investigated. Results show that: (i) risk using mainly upper-hard part, while there no part; (ii) after excavation tunnel, slight occurs first area vault, then gradually rises to strong level at 7 m behind working face, indicating hysteresis rockburst; (iii) vault surrounding effect forming deepest area, narrowing both sides, showing “V” shape, occurrence may not be completed one time; (iiii) borehole can significantly reduce tunnel. The larger diameter depth, better prevention. more significant than depth. research results provide guiding references similar underground engineering.