BRANCH SEGMENT

PROBLEM TO BE SOLVED: To increase the strength of a branch segment which is used in a multiple segment tunnel or the like and which must meet strict requirements for strength, without increasing its size. SOLUTION: The branch segment includes: a post connection (a) for joining the middle posts of a multiple segment tunnel; first end walls 1, 1 at each end along the width direction of the tunnel for composing a connection b along the circumferential direction of the tunnel; and a pair of second end walls 2, 2 which take approximately the shape of V when seen along the axial direction of the tunnel to compose a connection c along the axial direction of the tunnel. The segment is made of metal and has: an outer peripheral wall 3; a partial inner peripheral wall 4 connected across both second end walls 2, 2 to form the post connection (a); and an auxiliary inner peripheral wall 5 connected to at least two of the tunnel-radial-direction inner end of the first end wall 1, the tunnel-radial-direction inner end of the second end wall 2, and the post connection (a). COPYRIGHT: (C)2004,JPO