TUNNELS (Typical example of tunnels (underground train lines, road…
Typical example of tunnels
underground train lines
road tunnels (when there is an obstacle ex. a mountain or alternative to bridge
What are tunnels?
They are long and narrow underground passages with an opening at each end
What to consider before building a tunnel
condition and type of ground and groundwater
Who are tunnels built for?
What are the purposes ?
Main techniques to build a tunnel
Cut and cover
a trench is dug andthen covered with an overhead support system it is used for tunnels close to the ground surface (road tunnels)
the path of the tunnel is drilled horizontally
when the rock is firm
rock is hard
the tunnel is blasted out with explosives
ground is softer
tunnel shields (steel tubes the same size of the tunnel) are pushed into the ground to dig out the earth
They are built for pedestrian or vehuicular traffic (rail or road) and for canals