In article ,
"Kevin Brooks" wrote:

"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.

While I'm *sure* yours is, from the assumptions you made about
thickness. Height and overall mass is all well and good, but stress,
construction and *thickness* are the important issues for a Wallis-type
bomb. The Three Gorges, while very tall and very long, isn't as thick
as you seem to think.

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,

Actually, it was the *placement* of the bombs that caused the issues.
One bomb, well-placed, was more than enough in each case. Their aiming
system was a couple of spotlights and a piece of wood with nails in it...

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).

"Substantially" being about twice, at about the halfway point. Which is
why I mentioned a much larger weapon with a much more powerful
explosive. Fired off at a deeper location, double the water depth,
double the tamping effect, placed directly against the surface, you
should be able to get at least a factor of four more destruction, which
would do a lot to the twice-as-thick wall of the Three Gorges at about
halfway down.

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...).

Nope. As I mentioned, it's certainly a feasible thing to do. Not
airdropped (as I mentioned further into my post), but it's not hard at
all to place large items by hand, if suitably ballasted. A modern high
explosive would do a *lot* more damage than anything they'd try to use
in WWII. A higher propagation velocity would *magnify* the effects
versus WWII high explosives.

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).

....except that the thickness you're talking about is only at the
*bottom* of the dam. It slopes in a *lot* on the downstream side to
about the halfway point, where it's less than 100 feet thick (the
upstream side is a vertical wall from top to bottom). A two meter depth
*surface* crack in concrete is almost certainly not the only crack
you've got in a structure that size (besides the 80 surface cracks they
know of, how many are there deeper in?).

China isn't famous for good construction practices, and average over a
hundred dam collapses per *year*.

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 original DoD report only mentioned that Taiwan might hold the option
to attack various high-value targets (like 3 Gorges) in China if the
Chinese invaded Taiwan (as possible strategies), but the PRC has already
made some very strong comments. There are other sources than the one
minor one that started this thread.

"It will provoke retaliation that will 'blot out the sky and cover up
the earth,'" according to one general in the PRC, quoted in a lot of
places (Reuters story, June 16).

Note that the Pentagon report on this was from last year. Why the
strong comments *now*?

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.

Actually, it's not really that large. A good-sized truck would hold it.
Or a few bribes to one or more PRC officers to get some stuff that's
already handy. Not to mention that there was probably a few thousand
tons of TNT used during the construction of 3G, and diverting a fraction
of a percent of that wouldn't be too tough.

Hell, unless the PRC has some *extreme* measures in place, it wouldn't
be that hard to put a *hundred* ton bomb of some sort in a boat, steer
it to the dam, and sink it with a depth sensor for detonation...

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.