Concrete-lined tunnels

Hydraulic tunnel common lining type includes unlined tunnel, shotcrete tunnel, plain concrete lining tunnel, reinforced concrete lining tunnel, prestressed concrete lining tunnel, steel lining tunnel, etc. The unlined tunnel and shotcrete tunnel... 

There are, however, several important niche applications for CAC. Most notably, CACs are used as linings to sewers and mine tunnels. Calcium aluminate cements are resistant to chemical attack from sulfate-producing bacteria that thrive in sewer systems (especially in warmer climates), and sprayed concrete linings to sewers have been shown to resist degradation for periods up to 30 years. The high impact and abrasion resistance of CAC also makes it suitable as a lining material for ore tunnels in mines and because CAC sets rapidly, it can be sprayed onto tunnel walls (as shotcrete ) and even used as a tunnel lining. 

Ecob, C.R., King, E.S., Rostam, S. and Vincentsen, L.J. (1995). Epoxy Coated Reinforcement Cages In Precast Concrete Segmental Tunnel Linings - Durability. Corrosion of Reinforcement, in Concrete. C.L. Page, K.W.J. Treadaway, P.B. Bamforth (eds), 1990 Published for the Society of Chemical Industry by Elsevier Applied Science, London and New York, pp 550-558. 

Estimate the volume of the earth that has to be removed to make room for the 60-mi-long, 24-ft-diameter, concrete-lined water tunnel. Also, investigate the capacity of typical dump trucks used in removal of earth materials. 

For class III surrounding rock, under the tail-race tunnel maximum pressure, the maximum tensile stress value is 0.55 MPa. The plain concrete lining is safe and reliable. 

Guangzhou B (China) High pressure tunnel 610 8.5 600 mm reinforced concrete lining... 

Bath County (USA) High pressure tunnel 390 8.7 1000 mm plain concrete lining... 

For the other tunnel range (WO + 101.580 WO + 568.382), the engineering geological conditions are good, permeability is weak to micro, elastic modulus is high, and the internal water pressure is low, so the plain concrete lining is feasible in theory. 

For the hydraulic tunnel of domestic pumped storage power stations in China, the steel lining and reinforced concrete lining are mainly used, while the plain concrete lining is often used abroad. 

The 1994 Northiidge earthquake caused no damage to concrete lining of bored tunnels of the metro system in Los Angeles, CaUfomia (Hashash et al. 2001). 

The strain bending component is relatively small compared to axial strains, but if the tunnel radius increases, the curvature contribution increases. Tutmel cracks may open and then close in the lining due to the cyclic nature of the axial strains. As long as the cracks are small, are uniformly distributed, and do not affect the performance of the tunnel, even unreinforced concrete linings are considered adequate. It is important to emphasize that the p- and s-wave velocities used are those of the deep rock. The range for s-wave is between 2 and 4 km/s and p-wave between 4 and 8 km/s (Power et al. 1996). 

The principle employed is to drive a number of boreholes into the rock, load them with explosive and fire the explosive. This is known as drilling, charging and firing the round. The broken rock is cleared away and the length of the tunnel has then been increased by approximately the depth of drilling the boreholes. The length by which the tunnel is increased by each cycle of operations is known as the advance. As the tunnel advances, its inner surface is made smooth and secure by lining with steel and concrete, or other means. 

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