"Chad Irby" wrote in message
om...
In article ,
"Kevin Brooks" wrote:

If *your* interpretation of that is that it requires a weapon capable
of breaching a massive dam like Three Gorges, then you need a reality
check and some remedial reading comprehension work. That dam is over
180 meters tall, and contains some 26 plus *million* cubic meters of
concrete (more than *twice* the mass of the world's previous record
holder). It is designed to handle a 7.0 Richter scale event. Reality
check time--what conventional weapon do you know of, or can you even
conceive of, that could *breach* a structure of those massive
dimensions? Answer--none.

Actually, the answer is "a pretty big one, but not as big as you'd
think."

I believe your analysis is a bit faulty in this case; see below.


The Three Gorges is certainly very wide, and very tall, and quite thick
at the base, but if you hit it about halfway up with a full reservoir,
you could breach it with a moderately-large explosive package, since
it's only about twice as thick at midpoint as the Mohne dam was at the
point the Wallis bomb broke it.

The Wallis bomb was apparently good against a target that did not exceed
about 50-feet thickness at the point of detonation (see:
www.arnsberger-heimatbund.de/moehneattack.html ). The Mohne and Eider dams
challenged the ability of the Walls bomb to do the job, and as you note the
Three Gorges is substantially more massive (and you may be a bit low on your
estimate--remember that the dam crest sits about ten meters above the flood
stage overflow water profile, from what I have read).

Since the explosive for the Wallis bomb
was 6600 pounds, you could probably knock a big hole in the Three Gorges
with a ten or twelve ton bomb of more-aggressive explosive,

Now we are getting into fantasy land (I know, that is a place where Henry
usually enjopys playing, but still...). The point here was a Taiwanese
capability of delivering a warhead to the target and doing the deed--I doubt
the PLA would stand idly by while a Taiwanese transport aircraft (and that
is what it would take to deliver a weapon of the size you are indicating)
idles in bound towards the dam. Neither can you reliably count on the
relationship between explosive size and depth of breach being a geometric
relationship, either. There is a *reason* we planned on taking dams out with
ADM's back in the bad ol' days--they, along with large suspension bridges,
are just plain nasty targets to try and take out with externally emplaced
explosives.

maybe with a
shaped charge.

Nope. Shaped charges work lousy through water--the water disrupts the jet
formation. And shaped charge penetration has a couple of nasty
characteristics that further sink this option of your's--first, penetration
depth is based largely upon the diameter of the liner and acheiving the
optimal standoff distance (you'd need one tremendously large diameter liner,
and all of that water gets in the way of the jet formation, unless you are
arguing for hitting the "open" face, in which case congrats, you just
penetrated the concrete--to a max depth of maybe six or eight meters, that
is), and second, the jet actually creates a comparitively itty-bitty little
hole (maybe between one-tenth and one-fifth the diameter of the liner). A
shaped charge is a no-go, from the get-go.

Do that at one-third of the way down from the crest
(deeper than the Mohne, you get a lot more boost from the water
pressure), and you could flood central China with a bigger flood than
any recorded in history.

I don't think so, based upon the comments above.


There are some concerns about the construction or the 3GD (they had 80
fairly long, two meter deep cracks form when they started filling it).

OK, now you are arguing that the PRC themselves may have created a potential
future catastrophe in the making--plausible, but unlikely IMO (a 2 meter
depth crack is nothing if the thickness of the mass at that point is seventy
or eighty meters).


A moderately paranoid person might also consider that the Chinese
government could be dropping these "Taiwan may attack dam" stories in
order to give them someone to blame when and if the thing lets go on its
own.

But the source induicated for this discussion is not the PRC, but a DoD
report that included some musings accredited to Taiwanese, with TG merely
being offered as an example.


The largest bomb the ROCAF could deliver would be maybe a 2000
pounder, of which maybe half is explosive filler. Submerge that puppy
on the upstream side (a la the old Barnes Walls "Dambusters"
approach) and you'll be lucky to spall some concrete and kill oodles
of fish.

The sort of thing that would destroy the Three Gorges wouldn't be
air-deliverable by Taiwan, but would be easy enough to assemble upstream
and place with divers.

That is one big puppy you are talking about smuggling into the PRC,
assembling, and then getting into place. Not exactly what I'd call a
reliable military strike option.


Brooks

--
cirby at cfl.rr.com