PURPOSE: To enhance strength and waterproofness against an internal pressure by introducing prestress into a segment ring where an unbonded prestressing steel is buried in the longitudinal direction and filling up a sealing material into a clearance of a segment connection unit.
CONSTITUTION: Segments 1 are installed to a specified location one after another from below and the end of buried unbonded prestressing steel 4 is interconnected with a coupler 7, thereby assembling a segment ring. Then, a hydraulic jack is inserted into a clearance of notched parts 3 for a hydraulic jack insertion of the assembled segment ring and a hydraulic pressure is applied to every hydraulic jack, thereby expanding the segment ring in the circumferential direction and straining the prestressing steel 4. Then, a steel material, such as a steel plate is pushed into the expanded clearance, thereby holding the tensile force and relaxing and removing the hydraulic jack and introducing a prestressing force to the segment ring. The clearance of the notched parts 2 and 3 of the segments 1 is filled up with a sealing material, thereby integrating the adjacent segments 1 and preventing the water leakage of a joint unit.
WATANABE KEIICHI
FUJINO YUTAKA
ISHII TSUNEO
TOKU YUJI
NIPPON SHIELD ENG KK