[baumschubser]

I want to mention a recent extension to Berlin‘s subway system right in the middle of the city, in swampy ground and below a canal. They injected „freeze lances“ into the ground, turned 43,000 m^3 of mud into an ice block and then carved their way through it. Absolutely amazing engineering, I think planned and executed by a Swiss company.

[padenot]

This is also a technique that was used more than 100 years ago for the line 4 of the Paris métro: https://www.ratp.fr/en/discover/out-and-about/culture/histor...

[llsf]

Funny that they had to freeze the ground to dig it, as it is one of the hottest line in Paris (at least 20 years ago).

[s1artibartfast]

My understanding is that the freezing is normally about stopping water intrusion long enough to drill and place concrete

[pwarner]

Big Dig also used ground freezing. https://babelniche.com/2024/01/17/innovations-of-the-big-dig...

And the Erie Canal dig the sections through swampy ground in the winter. That was partially to avoid Malaria. Circa 1825

[Haemm0r]

Got a link for this? I am interested :-)

[getwiththeprog]

I can find https://www.berlin.de/en/news/8097068-5559700-stabilization-...

Which states that due to sandy soil concrete was injected with lances. It was done by a French company.

Might be the same tunnel?