"Howard Berkowitz" wrote in message
...
In article , "Keith Willshaw"
wrote:

"Howard Berkowitz" wrote in message
...
In article , (Al
Dykes)
wrote:



Some people might do well to look at the geology of Syria. The
flatter
parts are generally sandstone or an equivalent crumbly rock that won't
support tunneling much deeper than irrigation. A start was once made
on
a Damascus subway, but apparently abandoned because every tunnel would
have to be steel- or concrete-lined.


As is every tunnel on the London Underground, except for some of the
older tunnels were cast iron segments or brick linings are used.

The more mountainous areas are karst, which does tend to have natural
caves, but doesn't lend itself enormously to tunneling. Serious deep
excavations, like Cheyenne Mountain, are granite or similar hard rock.

You may wish to think again

London is built on clay, I guess that means you think they couldnt
possibly build the London Underground

No, I said _serious_ tunneling. Cheyenne Mountain is a good example of a
serious tunneling excavation (and other system) intended to withstand
near misses of nuclear weapons, or deep-penetrating PGMs with
conventional warheads.

I rather think that the hundreds of miles of tunnels
that make up the London Underground system are
really quite serious.

So were the Cabinet war rooms and the underground
military HQ in London and Northwood.

All built under clay



The sea bed under the English Channel is made of soft chalk.
Somehow though they managed to build a tunnel under it.

The technical breakthrough that makes tunnelling in soft
materials isnt exactly new . The use of a tunnelling shield
and brick lining dates in modern times was introduced
by Marc Brunel but the technique seems to have been known
to the Romans.

And won't have much effect on a modern penetrating or high blast weapon.

It wasnt suggested it would, however a 100ft of clay or
sandstone, especially if properly reinforces is rather
difficult to penetrate using conventional weapons.

Cheyenne Mountain isn't only granite, it's granite in a matrix of steel
stabilizing bolts. Zhiguli is presumably comparable.

I think the Syrians know about steel and concrete too.


In the middle east the techniques for building extensive
underground tunnels have been know since antiquity.
The network of irrigation tunnels in Iran are known
as the qanat and in Arabia they call them the falaj.

Exactly. The qanats are what I'm describing in the Syrian lowlands. They
don't and can't go deeply enough to withstand modern bombing.

But tunnels built using modern techniques can and do.

Keith




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