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The most important underground structures are tunnels, wells,
power plants, defensive installations, and ammunition dumps,
which have different specifications in formworks. These
structures have the same characteristics in underground
structures supporting. Some of the problems we confront during
underground structures executions are unfavorable conditions,
presence of water, lack of air conditioning, artificial light,
sound pollution and limited working area. For example, the most
effective factors in underground structure forms designing is
availability problems and limited working area so, during
drilling process the ventilator ducts, necessary area and lorry
traverse must be taken into consideration.
Designers should pay attention to the maximum iteration and ease
of mobility in limited space in designing the forms.
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Major Considerations
of Tunnel Formwork
Generally, according to the strength of rock, tunnel excavation
is done by mechanized or traditional methods. Different tools
and materials such as rock bolts and shotcretes are the first
maintenance equipment of preserving the tunnel at the first
stage of excavations. The duty of shattered is to create a layer
of reinforced and non-reinforced concrete on excavated rocks.
Mixture of cement, sand and water is poured to the surface of
tunnel walls by pneumatic pumps and makes a layer with a
thickness of 5 to 30 Cm according to the mechanical conditions
of tunnel rocks. In the next stage, which is permanent
supporting, concrete is one of the important materials used.
This stage is known as Tunnel Lining.
Tunnel Special forms are considered execution tools of tunnel
lining, which are designed according to the general conditions
of underground structures formwork.
Finished concrete surface of water tunnels must be prepared
smooth and flat to restrain hydraulic jump of fluid. If the
surface of concrete is rough, the liquid will carry it away. |
Tunnel
Form System