Posted by: sgolds
In reply to: CombJelly who wrote msg# 18057 Date:11/19/2003 2:01:59 PM
Post #of 18102
CombJelly, chipguy, blasting -
Building on top of an existing building does not require blasting, so that old expansion should not have bothered production. Whether or not a new building requires blasting depends on the ground conditions there - is there bedrock in the way? If the subsoil is silt, then it can all be done with bulldozers and such. I'm certainly not familiar with the intimate geology of Dresden so I don't know what is required.
The other big cause of earth movement - earthquakes - should not be a big consideration in central Europe. Actually, earthquakes can happen anywhere, although most frequent on the faults at the edge of tectonic plates. When they happen, production in progress can be greatly affected but the lessons from Taiwan are that only wafers at critical stages need to be trashed. The equipment itself is brought back up and running in a few days.
As i stated in an earlyer post. My brother was a contractor. My folks have been for years.
I visited DEC's fab in Hudson, MA while it was being built. A fab is much more involved than the heaviest comercial, factory, manufactoring type structure.
The floors were 3' thick and the re-rod mats were No-12 rod on 6" centers. Each mat had a 6" seperation from the one above/below it. Reenforcing rod is measured in 1/8" increments. A number 8 re-rod = 1" dia. Thus #12 rod = 1.5".
The walls were somthing to write home about allso. The structual steel, concrete, re-rod that goes into a fab is exponentially more than most any other structure, save a nuclear powerplant.
If an old foundation exists it either meets the criteria or it does not. If not, it may well be blasted for removal.
If bedrock exits close to the surface it will still be blasted to a depth that allows a 3'-4' floor to be poured so that the re-rod can be tied in with the walls etc.
If the site sits on silt or glacial till steel piles will be driven down to bedrock. Steel piles consist of 16" square H beams. A hard toothed SHOE is welded on so it can be driven into the bedrock enough to gain a solid hold. When I was a kid I had to shovel coal into a boiler to make steam for the steam driven Hammer, today they use diesel hammers.
Eartquakes can move mountains. A truck bouncing by a crappy fab can drive your optics nuts.
Jules
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