| 摘要 |
PROBLEM TO BE SOLVED: To enable the position of a propelling device to be detected using a laser target method while keeping high accuracy, without affecting the straight-going property of a laser beam. SOLUTION: This underground propelling device 1 has a laser target 3 provided inside its main body propelled into the ground, and digs a tunnel in the ground by emitting a laser beam toward the laser target 3 from a starting vertical shaft 4 through a laser path 7 in the main body, reading the position of the laser beam applied to the laser target 3 to detect the position of the propelling device 1, and controlling the progress of the propelling device 1 according to the position detected. In this case, a heat insulating layer 11 is provided around the laser path 7 in the main body of the propelling device 1, so that a group of electrical equipment 10 arranged around the laser path 7 is thermally isolated from the internal space of the laser path 7 by the heat insulating layer 11. |
