| 摘要 |
PURPOSE:To permit curved excavation of a given locus, with a small curvature radius even in soft ground. CONSTITUTION:In a tube whose longitudinal direction is divided into three sections, a front end 1a, a body 1b, and a rear end 1c, a cutter 5 is provided to the tip of the front end 1a, and the front end 1a and the body 1b are connected by three or more shield jacks 3 provided at an interval along the inner surface of the tube. The rear end 1c and the body 1b are advanced under ground by an excavator connected by three or more fixed jacks 4 provided at an interval along the inner surface of the tube. In such a work, the front end 1a is advanced under the ground by differentiating the strokes of the jacks 3 while turning the cutter 5, and the jacks 4 are extended and fixed by matching the stroke difference of the jacks 3. Under the condition, the body 1b and the rear end 1c are advanced to approach the front end 1a, and the excavator is advanced while repeating the excavating process of the front end 1a and the excavating process of the body 1b and the rear end 1c. |
