| 摘要 |
PROBLEM TO BE SOLVED: To make the outer shape of a body expandable/shrinkable and eliminate the interference between the inner face wall of a tunnel and the outer peripheral face of the body by moving multiple support bodies split in the peripheral direction along the radial direction. SOLUTION: When the outer diameter of a body is to be shrunk as required, side support cylinders 18-21 are driven to shrink cylinder rods, and side supports 13, 14 are rotated inward while their connection sections to a lower support 25 are used as fulcrums. A roof support cylinder 25 is driven to move the support main body 12a of a roof support 12 inward. Support connection sections 12b, 12c are moved inward to the side supports 13, 14 side, and the shrinkage of the outer periphery length caused by the outer diameter shrinkage of the body is absorbed. When the outer diameter of the body is shrunk and the interference between the inner face wall of a tunnel and the outer peripheral face of the body is eliminated, an excavation is restarted. When the body is somewhat advanced, the support cylinders 18-21 are driven, and the outer diameter of the body is returned to the original outer diameter. |
