Channel Tunnle

[hopalong]

I know it's not likely but if the Channel Tunnel collasped or split where would all the water go?

[Dreddnaught]

It would fill the tunnel until it found its own level.

Water will always find its own level, so don't worry, theres no danger of the English Channel gushing into england and france should something happen to the tunnel.

[Skids]

Its own level being sea-level in the English Channel.

[brachiopod]

Where would all what water go?

The channel tunnel does not contain any water.

La Manche / English Channel / North Sea contains alot of water.

Should the tunnel rupture it would fill up with sea water from the channel with a significant effect on whomsoever happens to be travelling through it at the time. The effect on the volume / sea level or otherwise of the Channel would be totally insignificant.

 

[brachiopod]

Ok, I am sufficiently drunk to do your research for you.

The 'Channel Tunnel' consists of two rail tunnels, and a service tunnel between them. (I didn't neeed to google thus far).

So, for each tunnel, we have a volume of;

(pi x diameter/2)� x length ie the volume of a cylinder

The two rail tunnels have an external diameter of 8.2m *� (we shall ignore the volume of the concrete lining), and the service tunnel a diameter of approximately 5m (exact internal and external dimensions are not so easy to find - I have conflicting internal measurements of 4.8m and 5.0m *� )

The sub-marine section of the tunnel has a length of 37.5km.

Therefore, the total volume of the two rail tunnels is;

(pi x 8.2 / 2)� x 37,500 x 2 m� = 12 443 082 m�

and the service tunnel;

(pi x 5.0 / 2)� x 37,500 m� = 2 313 185 m�

adding these together;

= a total volume of  14 756 267 m�

 

*� - http://www.engineering.com/content/ContentDisplay?contentId=41007026

*� -  http://www.geologyshop.co.uk/chtunfacts.htm

[cont....]

[brachiopod]

So if the tunnels were to rupture, then nigh on 15 million cubic metres of sea water would flood in. This may seem like a lot, so let's put it in context.

Defining the boundaries of the Channel with the North Sea and the Atlantic is, at best, arbitrary. So, for the sake of argument, we will say the Channel extends from Dover to Portsmouth, a longitudinal extent of some 160 km. the narrowest part of the Channel is the Strait of Dover, (between dover and Cap gris-Nez), at 34 km.

Assuming (very generously) that this is the constant width of the channel, this gives us a surface area of ;

160 x 34 km� = 5 440 km� = 5 440 000 000 m�.

So, spread over this underestimated area, the 15 million cubic metres of sea water that would flood into the Channel tunnels, (should they rupture), would actually lower the sea level of the Channel (as defined above) by;

14 756 267 / 5 440 000 000 m

=0.00271 m

or just under 3mm (yes, millimetres).

[hopalong]

Thanks to all and to Brachiopods thanks for taking your drunk time to research that for me. ;-)

[Potatoman]

brachiopod, that has got to be the most detailed answer iv ever seen!

[Thunderchild]

u got the calculation wrong for the area of a circle its not the square of pi X d/2 but the square of d/2 X pi otherwise congratulations on ur figuring

[landie]

Who would notice 3 mil when tides are taken into account. However the water from outside of the English Channel (Atlantic, North Sea etc.) would easily make up for any such loss very easily with no resultant drop in level.

[genesis59]

Brachiopod - Absolutely Marvellous!!! Great Stuff.

[PatTheRat]

So surely on the other hand, when the channel tunnel was pu in place it made the level of the sea rise ever so slightly, so the water would then go back to rougly what it was before (excluding all other factors).

[landie]

I don't believe they excavated any significant amount of water when creating the tunnel. They must have put the soil and rock somewhere though.

[jjaammeess]

thunderbird is right------ your calculation is 3 times too big because it is pi not pi squared

[Thunderchild]

so then the water displacement is less than 1 mm not forgetting that the channel is in direct comunicatoin with all the sea in the world so the difference in level would be null especially if u consider the effect of the tide

[d-signet]

The french would push it all over to us

[kool_kirsty]

I saw your question and I thought that the obvious answer is that if the channel tunnel collapsed the water would not need to go anywhere cos the tunnel is under water and the water would just fill into the sea.

[greg-williams]

The tunnel is a minimum of 45m below the sea bed and was cut through gault clay, the clay itself is impermeable and therefore water cannot get through. There are no tactonic plates in the area so an eathquake strong enough to disrupt the clay is not possible and an explosion would find the path of least resistance and travel along the tunnel and not outwards. In short, it couldn't happen :)