Stability Evaluation of TBM Pilot Tunnels to Rear Blasting Using the Protection Shield

Recent studies have increasingly investigated construction methods for tunnel excavation because of growing underground space development. Although the New Austrian tunneling method (NATM)—a representative method—can be applied to various ground conditions, as well having good constructability and economic feasibility, it suffers from problems such vibration noise. By contrast, using a boring machine (TBM)—a mechanized method—affords advantages stable excavation, minimized environmental damage, noise, vibration. However, cannot easily high costs delays owing equipment defects. Therefore, simultaneous pilot TBM—which affords constructability, noise vibration—and rear enlargement blasting NATM was in this study. A protection shield installed minimize accidents occurring defects (a disadvantage TBM) analyze decrease effect blasting, which depends on use separation distance through 3D numerical analysis.