ABSTRACT
TBM(Tunnel Boring Machine) is an useful machine to construct the tunnel. In the excavation by TBM, the rock is broken by the disc cutter installed on the cutting face of TBM. Recently, the round tip disc cutter has been widely used. This paper describes the rock cutting by use of actual size disc cutter with round tip. It was confirmed that hard rock can be broken by the round tip disc cutter. Furthermore, the internal of the rock was visualized by X ray CT equipment. It was observed that the fracture was generated horizontally from the dip made by the rolling of the disc cutter.
