| 摘要 |
PURPOSE:To prevent the destruction of a pit wall due to a cutting pressure and shorten the construction period in excavation by installing a shield plate, etc., under a cutter head for excavation and commonly using an excavating machine in the excavation of a pilot pit and a reaming pit. CONSTITUTION:A pilot pit A having a small aperture is drilled by an excavating machine body 1. After the completion of drilling, a cutter hrad 4 for excavating a reaming pit is installed in substitution for a cutter head for excavating a pilot pit. A reaming pit B as main pit is drilled by using the same excavating machine body 1. On the directly under side of the cutter head 4 for excavating the reaming pit, a shield plate 10, etc., are prepared beforehand. In accordance with the excavation of the reaming pit B, the shield plate 10 is shifted to the underside, together with the excavating machine body 1. Excvation is continue, always shielding the corner part pit wall of the pilot pit A by the shielding plate 10. |
