Inverted arcology
- Thread starter coliver988
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saundby
SOC-14 1K
Fun idea, but Mexico City?
I don't hold a lot of confidence in the ability to construct, much less maintain, such a structure there. Elsewhere, perhaps--but Mexico City has smaller problems than a 300-meter deep basement to pump out that they can't solve now.
Still, if this moves forward, best of luck to them.
I don't hold a lot of confidence in the ability to construct, much less maintain, such a structure there. Elsewhere, perhaps--but Mexico City has smaller problems than a 300-meter deep basement to pump out that they can't solve now.
Still, if this moves forward, best of luck to them.
far-trader
SOC-14 10K
So, isolation from earthquakes, countering water infiltration, and density/support issues.
Would floating the thing in the hole work? Basically build a form fitted boat and fill the unused clearance volume (several meters of clearance all around?) with water. Use the water as a feature at the surface (small ring lake) and for temperature moderation below.
Would floating the thing in the hole work? Basically build a form fitted boat and fill the unused clearance volume (several meters of clearance all around?) with water. Use the water as a feature at the surface (small ring lake) and for temperature moderation below.
BlackBat242
SOC-14 1K
Better give it a double-hull (shell?).
Mexico city is located in the heart of the the Trans-Mexican belt... it's built over the top of an older city (Aztec?) in a volcanic basin that once held a lake (mostly man filled), bracketed by at least two volcanoes - at least one is active (if not both). But, a little thing like sense never stopped man from building in dangerous locations 
As to 'floating' it in water, that would be a very bad idea - water is incompressible and its density would be different from the surrounding medium, causing magnifying and erratic reflection effects to surface and sub-surface shock waves.
However, such a structure could be built to withstand earthquakes, which would involve the structure 'floating' using traditional tech.
It would have an advantage in the sense that no man-made structures would sway into it - as long as none land atop it. Being covered by volcanic ash could be an issue, but then again, there may be advantages to an underground structure with its existing air requirements. Given the distance and intermediate structures, mudslides or even lava flows might not pose serious risks.
However, I don't think this is a serious plan - just someone's creative proposal...
As to 'floating' it in water, that would be a very bad idea - water is incompressible and its density would be different from the surrounding medium, causing magnifying and erratic reflection effects to surface and sub-surface shock waves.
However, such a structure could be built to withstand earthquakes, which would involve the structure 'floating' using traditional tech.
It would have an advantage in the sense that no man-made structures would sway into it - as long as none land atop it. Being covered by volcanic ash could be an issue, but then again, there may be advantages to an underground structure with its existing air requirements. Given the distance and intermediate structures, mudslides or even lava flows might not pose serious risks.
However, I don't think this is a serious plan - just someone's creative proposal...
Soil liquefaction during a seismic event would doom it. Regular hydraulic pressure could be vented and a bituthene type barrier used to keep it from shipping water. Structural stability is a big issue, huge piers to bedrock would not do it I bet, it would probably need compressors to freeze the mud to permafrost like they do in NYC. Even then it's not a low energy design because it would need heat all year round as it gets cooler the deeper you go and Mexico City's grid is already stressed and the air quality abominable.
Actually, Dragoner, the temperature will climb with depth, not drop.
There's an article online about the geothermal profile of Egypt, which is similar climate to Mexico City and surrounds... an average drop of 1.2°F per 100 feet from the mean annual surface temperature.
Only in places where MAST is below freezing do you develop permafrost... and dig far enough below, and you get warm again.
The upper 30 feet or so vary with current temperature. Freezing the 70+° soils is going to be a nightmare task... it's unlikely to even be attempted.
Fortunately, a design like the one pictured, provided it maintains shell integrity, will, like a boat, float when the soil liquifies. It may wind up ABOVE where it started....
There's an article online about the geothermal profile of Egypt, which is similar climate to Mexico City and surrounds... an average drop of 1.2°F per 100 feet from the mean annual surface temperature.
Only in places where MAST is below freezing do you develop permafrost... and dig far enough below, and you get warm again.
The upper 30 feet or so vary with current temperature. Freezing the 70+° soils is going to be a nightmare task... it's unlikely to even be attempted.
Fortunately, a design like the one pictured, provided it maintains shell integrity, will, like a boat, float when the soil liquifies. It may wind up ABOVE where it started....
I would think during an event, the rapid build of pressures it would fail, such as twisting in half, or at least trying to. Interestingly enough, all structures are like boats, float in soil unless anchored in bedrock and break their back along their keel (center beams) dying like boats do. Temperature wise I was thinking just about caves, where the temp can be a bit lower, not anywhere near freezing, however. I wonder what temperature the mud in Manhattan is, which they freeze to set buildings on? One thing is that soil temps are fairly stable so that even in winter, at depth the soil wouldn't freeze, winter in the lower 48, the frost table only reaches down a few feet, not more than 10 iirc.
It is still a neat building and interesting concept, reminiscent of the Mars books where they lived in pits. In Traveller we have grav cities, like in the TTA book or Ringworld, the migrating city actually sounds a bit natural.
It is still a neat building and interesting concept, reminiscent of the Mars books where they lived in pits. In Traveller we have grav cities, like in the TTA book or Ringworld, the migrating city actually sounds a bit natural.
Actually, if the city will float, then why not just build it in the Gulf of Mexico. No volcanoes, no earthquakes and 4 days warnig before a possible Hurricane (Which the oil rigs seem to ride out just fine).
(and the frost line is 6 feet deep in Baxter, Minn. - the coldest place that I have done work in.)
(and the frost line is 6 feet deep in Baxter, Minn. - the coldest place that I have done work in.)
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A city floating in mud can have aggregate density in excess of 2, often 3. A city floating in salt water can't exceed 1.05 or so...
A floating Mexican city in the gulf.....
The real reason would be why?
It is standard practice to exceed the frostline by 30-40%, for trenching utilities, footings, etc. .
