Abstract
Block Theory, which can find falling or sliding blocks by intersecting structural discontinuity, was applied for the excavation of large scale underground rock cavern. This paper proposed the procedure how to observe the excavation surface, to search key blocks and then to design support system. This method was executed during the excavation of Okutataragi underground power station, and detected key blocks were supported by shotcrete, rock bolting or rock anchor. It is shown that the proposed method based on block theory can help to reduce an amount of supporting system and to design the structures of rock cavern properly in discontinuous rock mass.
