In article , "Keith Willshaw"
wrote:

"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

When were they built? Were nuclear weapons or penetrating PGMs design
consideration?

I certainly agree they are stable under normal conditions, and, for that
matter, the German bombing of WWII. I'm not as convinced that 617
Squadron, using the Tallboy, couldn't have broached them, much less if
more modern weapons were used.



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.

The interim "bunker buster" rigged from old artillery barrels penetrated
over 100 feet of hardened clay (caliche) in the US trials before
deployment. They never did dig it out.

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.

I didn't say steel and concrete, but steel and granite. Cheyenne
Mountain was selected, in part, because it is a mountain, and it was
possible to tunnel in from the side. Even so, there was a significant
amount of construction (and excavated rock and soil) that would have
been visible in overhead imagery. I find it hard to believe that Syria
could have (1) found an appropriate granite mountain and (2) hidden from
satellites the evidence of building a major shelter.

What is plausible is that the Syrians might have improved some of the
karst caves, which would be much more hardened than the sandstone
through which the qanats are built. Improved karst, however, isn't the
same as reinforced granite.

I will grant that you can superharden something of the size of an ICBM
silo with steel and concrete, although some of the techniques need
research. Again, the construction is difficult to hide from
overheads--it is much more distinctive than a truck of mystery materials.


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.

If the Syrians did build such a complex, I suspect we would know about
it. We tracked their attempts to build a subway system, which were
abandoned.