PROBLEM TO BE SOLVED: To safely and surely perform jacking construction without making sediment and underground water flow out in a starting shaft from the outer periphery of a shield machine and a jacking pipe, in jacking work under deep-depth and high-water pressure.;SOLUTION: This invention is a starting pit mouth wall composed of a cylindrical body having a predetermined length in the jacking direction and having an inner diameter larger than the outer diameter of the shield machine and a jacking pipe, a plurality of seal brushes arranged in a plurality of places at predetermined intervals in the jacking direction in a cylindrical body so as to be adjacent in the circumferential direction in the cylindrical body, and a ring-shaped elastic body seal having the periphery fixed to the rear end of the cylindrical body and having the inner peripheral side abutting on the outer peripheral surface of the shield machine and the jacking pipe.;COPYRIGHT: (C)2006,JPO&NCIPI
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