How is the water initially displaced? And do they float? Attach to the bottom of the body of water?
I was driving through one today in Boston and couldn’t help but wonder. Cheers in advance!
In: 190
There are different ways to make tunnels under water in the same way there are to make tunnels under land.
Bored tunnels are the same as bored tunnels under land, they dig though the ground under the water using a tunnel boring machine. The Channel Tunnel was made this way.
Immersed Tube tunnels are roughly analogous to cut and cover tunnels on land. They dig a trench into the bottom on the body of water, then bring in sections of what are essentially a big pipe float them into position over the trench, and fill them with water so they sink. Then they are joined together and covered to protect them and stop them from floating and the water is pumped out. Sometimes the trench is deep enough that the bottom of the water body is flat after the tunnel has been covered (Like a cut and cover tunnel), and other times a ridge is left. The Osreund crossing includes a tunnel that was made this way.
There’s also an idea called a submerged floating tunnel. This is a big pipe like the immersed tube, but instead of being held down to the bottom by stuff piled on top of it, it floats between the surface and the bottom, held down by cables. It’s sort of like an upside down suspension bridge. It would allow for crossing bodies of water that are too deep for normal tunnels.
Latest Answers