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General design considerations
The main features that make deep underwater tunnels different from land tunnels are the reduced accuracy of underwater geological investigation, the great length of uninterrupted single drives, the high pore water pressures and seepage gradients at the tunnel elevation. ...
In designing the tunnel a number of considerations should be taken into account. ...
As this tunnel will be underwater there will be a need for an extra tunnel for people to use during an emergency, to escape from the road tunnel.
Another design consideration is if you are going to have one (traffic in both directions) or two tunnels (a tunnel for each direction) for traffic
If you have two tunnels you can just close one of the tunnels down in an emergency, which means that the traffic in the other tunnel will still flow and that emergency vehicles could use the other tunnel to get to where they are needed much quicker and easier.
However one tunnel is easier to build underwater. ... Also you could build the escape tunnel wide enough to allow the passage of emergency vehicles to the scene. ... With an underwater tunnel the ventilation should be provided by a mechanical means. Any ventilation system must dilute contaminants during normal tunnel operations and control smoke during emergency operations Emergency ventilation will be used in the event of a fire where it should remove and control the smoke and hot gases, making it easier for motorists to evacuate, allowing emergency crews safer access and protecting the structure of the tunnel. AS the channel tunnel is long you would have to divide the tunnel into sections, so where there were no cars or the cars had driven away you could divert any ventilation from that section to a section which needed more ventilation.
Other design considerations are that there should be lay-by’s at least every 1000 m, you should also have a hard shoulder all the way down the tunnel for cars that have broken down. ... These emergency exits could be short perpendicular escape galleries to a parallel safety tube.
To actually build the tunnel you will be building sections of the tubes in a ship yard (of roughly (40ft in diameter and 300ft long). The actual walls of the tunnel would be made of steel reinforced concrete. While people were building the tunnel on dry land, a dredging machine was digging the trench that the tunnel would be lying in.
Approximate Word count = 1952
Approximate Pages = 7.8
(250 words per page double spaced)
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