抄録
Bench blasting operations were carried out above a lined tunnel in a land reclamation site. The 400m long, 5.5m wide tunnel was temporarily constructed for muck transportation. The ground was excavated by 3m-step bench blasting and the excavation ended at 1m above the tunnel crown. Various parameters were monitored during excavation. In this paper, the results of field monitoring are presented. It was observed that no cracks appeared in concrete lining at particle velocities of less than 40kines (cm/sec) and the lining was damaged in the velocity range 40 to 100 kines. It was confirmed that the tunnel deformed elliptically towards the ground surface under the unloading conditions.
