Hi, Audrey. Frozen water can move mountains and break them up into little pieces. Water expands as it freezes. Frozen water between two "immoveable" objects will cause them to move, break or be subject to tremendous stress.
When you are digging foundations, you have to build it deeper than the deepest that your ground will freeze. If there is water under your foundation and it freezes, it will try to push the foundation out of the ground. Obviously, moving the foundation around is not good for your building.
You have to have freezing weather for a while to have a deep frost line. For example though, the frost line in Minnesota is 48". In southern Michigan, it is 42". I doubt that yours is very deep in comparison.
Since you have to go from the coldest winter on record, your weather bureau may be of some help on this. You might also do a search of the web to see what you can find.