Just to clarify, High Rise Beach condos are NOT built "on sand"

[WarGamer]

It's not your Ranch or Craftsman home with a concrete slab or raised foundation.

These buildings are supported by concrete columns extending INTO LIMESTONE ROCK 50 feet, 100 feet... sometimes even 150 feet + deep.

Rising Seawater. So? Engineered Marine Pilings last 30 years+ and that's a piling like at a pier in the ocean.

Whatever happened in Miami was NOT the deep foundation.

I'd bet it was a design flaw from the 80's or water damage to ground level support structures, possibly from a leaking pool/irrigation/rainwater, etc... or a combination of both.

Good reading here:

https://www.miamiherald.com/news/business/article17333627.html

Contractors building the 62-story One Thousand Museum condo tower drilled to Miami-Dade County-record depths earlier this week to lay the foundation for the ultra-luxury downtown building, the project’s developers said.

Workers at the construction site on Biscayne Boulevard drilled two shafts into the earth — one at a depth of 177 feet, the other at 171 feet — for pilings that will support the 709-foot-high building. The rest of the tower’s 225 shafts went down 155 feet, the required depth for its height.

The previous record for depth was 158 feet, held by the 60-story Porsche Design Tower in Sunny Isles Beach.

[msongs]

1. maybe these people could use roman style salt water concrete

https://time.com/4846153/ancient-rome-concrete-cement-seawater/

[WarGamer]

2. amazing, isn't it?

Never ceases to amaze me when I visit Rome or Pompeii...

[lagomorph777]

3. That shit is amazing.

There are Roman piers still around today.

[LifeLongDemocratic]

5. Lead

Romans also used lead piping in their water systems

[Mariana]

9. What does that have to do with the longevity of the buildings? nt.

[DBoon]

6. We just need to import lots of volcanic ash from Italy

[msongs]

10. we have mountains of it in hawaii nt

[smirkymonkey]

4. Yes, it's limestone, but it's very pourous limestone.

It is still prone to flooding, even when there are no storms or heavy rain.

https://www.businessinsider.com/miami-floods-sea-level-rise-solutions-2018-4

*Miami and Miami Beach already struggle with serious flooding related to sea-level rise — even when there is no rain.
*The ground under the cities of South Florida is largely porous limestone, which means water will eventually rise up through it.
*The cities are taking flood-control measures like installing pumps, raising roads, and restoring wetlands.
*Coastal cities around the world face similar problems.

It doesn't matter how deep they go if the seawater is going to bubble up from that pourous bedrock and start eroding those concrete columns, which it did. It weakened them enough to cause the collapse.

[sop]

8. I understand these underground foundations are designed to have waterproof barriers.

If the barriers fail, then the foundations are subject to corrosion.

[sop]

7. Romans didn't use steel reinforcing bars inside their concrete.

Interesting short article about what makes Roman concrete so durable:

https://www.sciencemag.org/news/2017/07/why-modern-mortar-crumbles-roman-concrete-lasts-millennia

[ecstatic]

11. Could the drilling have triggered a mini quake?

Which then brought the tower down?