Tunnel wall structure

Claim 1

A tunnel wall structure comprising a plurality of rings, each said ring having an axis and being comprised of a plurality of arcuate segments of reinforced concrete having circumferentially opposite ends and axially opposite sides with respect to said axis, circumferentially adjacent segments of each ring having circumferentially abutting ends, said plurality of rings being axially adjacent to one another and axially adjacent to said segments of said rings having axially abutting sides, first joint means between said circumferentially abutting ends comprising a pair of circumferentially opposed joint members each embedded in a corresponding portion of said abutting ends, said joint members having aligned central bolt holes opening circumferentially therethrough, said first joint means further including anchor members secured to said joint members and extending circumferentially therefrom into the corresponding segment, and a first bolt extending through said aligned central bolt holes and receiving a first nut to hold said circumferentially adjacent segments together, and second joint means between said axially abutting sides of said axially adjacent segments, said second joint means including aligned curved bolt holes extending axially through the abutting sides of said axially adjacent segments, a concave positioning member secured on each of said abutting sides of said axially adjacent segments, said positioning members having openings aligned with said curved bolt holes and being in mating engagement with one another, and a curved second bolt extending through said curved bolt holes and said openings through said positioning members, and said curved bolt receiving a second nut to hold said axially adjacent segments together.