Starnberg, a German town in Bavaria, will build a tunnel. The main problem is Starnberg area is partially a seeton area like in the lakebeds. A tunnelling nightmare. If not stabilized, seeton could cause the entire tunnel structure to sink. Solution by the State Building Authority is seeton stabilizatón using the jet spraying process.

The German engineers have tested this by drilling holes down to a depth of up to 22 meters. Then they spray the concrete and at the end create concrete columns of about two meters of diameter.  They will create such columns with a few meters of distance and they will get enough structure to withstand the weight of the portals and other tunnel structure.

This procedure will have no adverse effects on the groundwater.

https://www.merkur.de/lokales/starnberg/starnberg-ort29487/fuer-starnberger-tunnel-bau-saeulen-im-seeton-13837105.html