| 摘要 |
PROBLEM TO BE SOLVED: To provide a reinforcing steel pipe capable of shortening a work time by dispensing with a consolidation material press-in step and capable of reducing costs.SOLUTION: In an auxiliary method for excavation, a reinforcing steel pipe 10, which includes a slit part 24 for diameter enlargement, capable of enlarging a diameter in an axial direction, is driven into natural ground ahead of an excavation face of a tunnel to reinforce the natural ground ahead of the excavation face. In the slit part 24 for diameter enlargement, a plurality of slits 28 for diameter enlargement, which have given lengths in the axial direction, are formed in a circumferential direction.SELECTED DRAWING: Figure 1 |
