Overview of Tunnel Lining

Necessity and function of Lining

·       Structurally, to support the exposed ground

·       Operationally, to provide an internal surface appropriate to the function of the tunnel

·       Lining takes up rock pressure

·       Provides protection against rock splitting

·       Protects the rock against the aggressivity of water

 

 

Materials used for lining

·       Cast insitu concrete

·       Brickwork

·       Masonry

·       Cast iron

·       Steel

·       Shotcrete

 

 

Requirements of a good lining

·       It should be able to sustain loads

·       It must be durable and give the intended life of the tunnel

·       It must be watertight against maximum pressure of ground water

·       It should be economical

 

 

Loads on tunnel linings

·       Vertical pressure

·       Horizontal pressure

·       Pore water pressure

·       Seismic effects

·       Internal and external pressures

·       Rock stratification

·       Depth of cover

 

 

Theories regarding rock pressure

·       Terzaghi’s theory of horizontally stratified rocks

·       Fenner’s method

·       Beirbaumer’s theory

·       Terzaghi’s rock pressure theory

·       Protodyakonav’s theory

·       Kommerell’s theory

·       Suquet’s theory

 

 

 

 

 

 

 

Types of tunnel linings

·       Design considerations

·       Common support types

·       Cast Iron linings

·       Concrete linings

·       Steel supports

·       Shotcrete