Tunnel form systems
Tunnel form systems are used to construct repetitive cellular structures (such as hotels and apartment blocks) and enable the construction of horizontal and vertical elements (floors and walls) together. Each unit is in the form of an inverted L, the vertical leg being the formwork for one face of a wall and the horizontal leg being soffit formwork. Several units are erected together to create the formwork for a number of ‘tunnels’ consisting of walls and ceiling slab. The normal dimensions of tunnel form units are 8 to 11m long and 2.4 to 6.8m wide, but individual units can be joined to give tunnels of greater length. The forms are positioned, reinforcement is fixed and the concrete poured and cured. When the concrete has achieved sufficient strength the forms are lowered and moved to the next location.
Further information may be found in Formwork for modern, efficient concrete construction, by Rupasinghe and Nolan, published by BRE Press and in the CONSTRUCT A guide to the safe use of formwork and falsework.