| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for excavating the foundation by rotating a cutter head while pressing the cutter head against the foundation, which can prevent the damage of the cutter head at a low cost.SOLUTION: A columnar or cylindrical tunnel excavation device for excavating a tunnel on the foundation comprises a cutter part 30 at the tip which excavates the foundation by rotating around a center shaft of the tunnel excavation device. The cutter part 30 comprises a roller bit 38 and a drilling bit 40 installed in a planar tip surface part 20A, and a protrusive rib 39 which is installed so as to protrude from the tip surface part 20A and which holds sediment so that the sediment produced by scraping of the foundation by the roller bit 38 and the drilling bit 40 can cover the tip surface part 20A when the cutter part 30 rotates.SELECTED DRAWING: Figure 6 |
