Tunnel permanent lining construction

The basic materials for tunnel lining construction are cast-in-place concrete, cast-in-place and prefabricated reinforced concrete, cast iron and steel. These materials are chosen according to conditions of construction area and tunneling methods. The lining has permanent application as opposed to temporary lining (mine working support). The shape and size of lining are defined by size, depth and function of the tunnel and sort of take up load (rock pressure, hydrostatical pressure, traffic load, etc).

Cast-in-place lining is mainly used for construction of tunnels with most complex structure and big cross-section. Precast lining is widely used for shield and erector-arm tunneling, mainly in subway tunnels.

Technological production schemes of concreting for tunnel construction are defined according to hardness of rock, tunneling methods, depth, length and appropriation of tunnel and applied mechanic machines.

The concreting of one section of Lagar-Aul tunnel in Amur region on the basis of factors above was performed after the following works were finished: excavation form was made as designed in the project, excavation consolidation by means of shotcreting; the installation of rock bolt support, film waterproofing and reinforcement cage; placing of formwork in permanent position and release material covering.

Tunnel lining waterproofing

Various types of waterproofing materials are used in modern tunnel construction. Solid waterproofing is made of waterproof building organic or synthetic film filter materials, synthetic resinous materials, and steel sheets.

Cat-in-place tunnel lining, placed in stable rock ground, protect from water by means of external waterproof installed before lining construction. After that reinforced framework is performed.

Formwork

Tunnel formwork "Saga Сogio" (Japan) is used for mechanization of cast-in-place concrete lining construction of single track railway tunnel, excavated to the full cross-section. The total length of formwork, 20,5 m, provides heading for 20 m. The width and height of the formwork are 5.6 m and 8.2 m respectively. Weight - 100 tones. Pneumatic motion engine capacity - 10.3 kW.

Tunnel formwork "Wortington" (Italy) is appropriate for mechanization of cast-in-place concrete lining construction of double track tunnel crown. Entrance size for traffic (finished): width - 3.6 m, height - 3.7 m. Formwork weight - 110 tones.

Technologies