LARGE DIAMETER TUNNEL CONSTRUCTING METHOD AND RING CUTTING TYPE EXCAVATOR

PURPOSE:To improve the efficiency of large diameter tunnel excavating work by arranging scrapers between a plurality of automatic rotary cutters, to use advanced tunnels and to discharge muck and feed covering concrete, and by excavating the internal side of a covered section after the concrete is placed and is hardened. CONSTITUTION:Between a plurality of automatic rotary cutters 4, 4... arranged on a ring-shaped beam 2, scrapers 5 are arranged, and the cutters 4 and the scrapers 5 are contrived to be run along the beam 2. Besides, in advanced tunnels A, B, a muck transporting pipe 10 and a concrete transporting pipe 9 are arranged. After that, earth excavated in the shape of a ring with the cutters 4 is discharged from the discharging pipe 10, and in the space of the excavated shell in the shape of the ring, concrete is placed and a covering section is formed. After the placed concrete is hardened, the internal side of the covering section is excavated. As a result, the place of high ground pressure, a large diameter tunnel, and the like can be efficiently excavated.