Dock floor heaving

I have visited 30 years old cold storage. They have 5 freezers (temperature -2F) and dock (temperature 37F). Freezers have electrical floor heating. Dock doesn't have floor heating. Recently, they found that dock floor have started heaving. Drilled the holes and found that in some places up 6 feet of frozen ground. Anybody heard about similar issues?

Interesting finding. We generally do not carry out floor insulation in dock area, but at the same time have done some projects in Indonesia wherein the client insisted to carry out insulation even below dock levelers.