Title: the Development of Precast Concrete Segments for Tunnels

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Publication: CIA

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Date: 2/13/2011

Abstract:
For tunnels constructed in soft ground by shield or tunnel boring machine (TBM), the tunnel lining will be formed with precast concrete segments or in the case of a thrust bore by precast concrete pipe sections. The demands imposed on the design and performance of precast concrete segments have increased with the rapid development of tunnelling techniques. With each successive development of such techniques, greater demands are placed on the tunnel industry to build larger tunnels under increasingly more onerous conditions. The specifications for precast concrete segments are therefore equally demanding in terms of strength, durability, watertightness and geometric tolerances. The first tunnel segmental lining was used in the 19th century and was made of grey cast iron. The development of precast concrete linings was prompted by the Second World War when there was a shortage of iron. The early concrete segments were modelled on the cast iron ones and the paper describes the development of precast concrete segments through to their current use.