San Francisco's Millennium Tower fix halted after further sinking observed

sfgate.com

14 points·perihelions··7 comments

Previous threads (all from 2016)

https://news.ycombinator.com/item?id=12206158 ("Millennium Tower is tilting, sinking")

https://news.ycombinator.com/item?id=12574107 ("In San Francisco, a Sinking Skyscraper and a Deepening Dispute")

https://news.ycombinator.com/item?id=13036377 ("Satellites Confirm Sinking of San Francisco's Millennium Tower")

I would not be anywhere near that building for any prolonged amount of time if I could help it.

There are too many people and organizations that have too much to lose by being overly optimistic about the state of the building’s structural integrity.

What exactly is the source of trouble for this building? Was it to code and just bad luck, or did they screw up along the way?

That question is still being debated.

I heard it was a rare foundation for such a tall building. Additionally the building is made of concrete making it even heavier putting excess pressure on the soils below.

The 2 leading theories are:

1) it has a floating foundation (in sand, not to bedrock), unique for this size of building in SF.

I talked to an architect once, and he acted like this would be ok. Guess not.

2) workers on the nearby tunnel "dewatered" the soil near the building. Changing the moisture level changes the resistance of the sand to weight.

Note that in an earthquake zone, soil "liquefacts" and settles, forcing water up, so it's terrifying that a large building rests on that. The building could literally plunge into the ground, or fall over during a liquefaction event.

See the videos from Kobe - waterfalls appear on top of the ground in liquefaction areas.

Btw, it looks like you're at least partially shadowbanned.

Reply on news.ycombinator.com