They do make something to thaw the ground, kinda like a radiant heat system for flooring. Short story of my experience with it.
I actually worked for a compnay here in Wisconsin that the owner promised a homeowner that we would have his project done for the Superbowl. Contract was signed early in November. 2300 sq ft patio, 2 16x16 pergolas, concrete pad for hot tub, etc. Ground froze and his solution was renting a giant heater for an outdoor system that is similar to radiant heat flooring to thaw the ground. 3 hours to setup with plastic, 2" glycol filled hoses, and two layers of frost blankets. let it sit for one day, took two hours to uncover with three guys. Spent the day building and had to shift from what we just built over about 5 feet. Over night everything we just built refroze. Basically he forgot to keep in mind (or listen to myself and our brick supplier) that when something freezes, it expands, so every night whatever wasn't kept thawed would heave. and if you use something not frozen to level to something that is frozen. When your unfrozen ground freezes, it will heave too. Creates a little step from each day.
$2000 for the rental later, he understood.