JOINT STRUCTURE FOR SEGMENT

PROBLEM TO BE SOLVED: To provide a highly rigid joint structure with which segments in a primary lining segment ring can easily coupled one another, and in which the joint has a high strength. SOLUTION: A joint structure comprises a reinforcing means laid between a joint panel 3 serving as a coupling surface 2a and a second joint panel 5 provided in a segment 2 so as to define a reinforcing zone 6 through which long bolts 7 can pierces when coupling surfaces 2a (joint panels 3) are faced to each other. With this arrangement, the segments 2 can be coupled together by fastening the reinforcing zones 6 with the use of the long bolts 7. Further, both reinforcing zones 6 and the long bolts 7 can eliminate occurrence of deformation of a joint panel caused by transmission of stress in the axial direction of the bolt, and accordingly, the segments 2 can be firmly coupled by simply fasting the reinforcing zones 6 wit the use of the long bolts 7.