To easily connect a reinforcing ring in a lining work of a vertical shaft by use of liner plates.

A joint 50 for a ring is constituted of a joint member 52 fixed to one ring piece 18a, a pair of fixed members 54 fixed to the other reinforcing ring piece 18b adjacent to the ring piece 18a, and a connection bolt 56 connecting the joint member 52 to the fixed members 54. And the joint member is constituted of a joint plate 58 and two connection pipes 60 fixed to the joint plate 58. The joint plate 58 is provided with an extended part 58b overlapped on the outside flange of the ring piece 18a. The connection pipe 60 is fixed to the extended part of the joint plate 58. The fixed members are fixed so as to hold the extended part of the joint plate therebetween. Holes are coaxially formed at the opposite positions of the ends of the connection pipes 60 in the fixed members 54 respectively. The connection bolts 56 are inserted in the holes and the connection pipes 60 to screw the front end of the connection bolt 56 in one of the fixed plates 54.