| 摘要 |
<p>A shield tunnelling apparatus comprises a first tubular shield body (12) in which a cutter assembly (26) for excavation and a drive mechanism (28) for driving the cutter assembly are disposed, a second shield body (14) connected to the rear of the first shield body so as to have the common axis as the first shield body, a target (42) disposed in the first shield body so as to receive a light ray directed toward a direction along the axis, first optical path changing means (54) disposed in the second shield body and changing the optical path (40) of the light ray directed toward the target such that the light ray travels along the optical path displaced away from the axis, and second optical path changing means (56) disposed in the second shield body and changing the optical path of the light ray passing through the first optical path changing means such that the light ray is directed toward a direction along the axis. <IMAGE></p> |
