MULTIPLE MIDDLE-FOLDED TYPE SHIELD EXCAVATOR

PURPOSE:To raise the sealing efficiency by method in which a shield frame is made up of cylindrical subshield frame bundles, and the subshield frames are divided into front and rear cylinders and connected, and a middle-folded seal is provided to the connection. CONSTITUTION:Two cylindrical subshield frames 1 are vertically stacked and bundled by an outer cylinder frame 2 of a glasses-like shape. A subshield frame 1 divided into a front cylindrical subshield frame 1a and a rear cylindrical subshield frame 1b is provided before and after the excavating direction in a bendable manner by a middle-folded jack 4. A middle-folded seal 7 is provided to the connection 6 between the frames 1a and 1b. In this case, the force imparting to the seal 7 from inside to outside, as shown by arrow mark 10, when the frame 1b is inserted, can be dispersed due to its annular form. The sealing function can be thus be raised, and the excavation can be attained in a steeply curved state of a great curvature radius.