Precast Shaft and Tunnel Linings
Precast concrete segments units are used to form the permanent lining for tunnels and shafts. A variety of forms are available depending on the size of the structure, the method of construction and the soil conditions. Units are generally reinforced to deal with normal handling and erection stresses, using steel reinforcement.
Units can be produced with steel fibre reinforcement when the design shows that this is a viable alternative to conventional steel reinforcement.
See PAS 8810:2016 Tunnel design. Design of concrete segmental tunnel linings. Code of practice.