Ulma MK Structure - Page 11

Construcción
ConstrucciónConstrucción
Construcción
11
MK
MK MK
MK STRUCTURE
STRUCTURESTRUCTURE
STRUCTURE
1.2.4. CUT
CUTCUT
CUT-
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-AND
ANDAND
AND-
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-COVER TUNNEL FORM CARRIER
COVER TUNNEL FORM CARRIERCOVER TUNNEL FORM CARRIER
COVER TUNNEL FORM CARRIER
The solution with the MK system for cut-and-cover tunnels can be regarded another type of form carrier adapted to
the particular requirements of tunnel construction where the structure must adapt to the vault shape of the tunnel.
This form carrier type also applies to applications where walls and slabs are cast at once as it is the case of
rectangular section tunnels.
Vaulted tunnels are usually not cast at once but in stages: first the gables then the top part of the vault. Cut-and-
cover tunnel form carriers are complemented with swivel parts to facilitate the stripping and forward-moving of the
structure.
An all-round solution for cut-and-cover tunnels combines the MK Structure system for the top part of the vault
with the MK Shoring system. A cut-and-cover tunnel form carrier usually consists of the following parts:
o Main structure: structure bearing the concrete load, both the vertical as well as the horizontal loads.
o Forward-moving structure: secondary structure which effects the movement and bears the forces
during such.
o Bracing: components that withstand wind effects and transverse movements.
o Formwork: part in touch with the concrete shaping it, allowing its adjustment and opening if this is
required for the movement of the structure.
o Rolling and levelling system: components that enable the rolling of the truss and its levelling at a
specific place, as well as its stripping.
o Safety items and access: walkway platforms, handrails etc., depending on the requirements of each
project.