propofol

We are just having a pool installed at our house. In-ground, in the backyard. We live in Ontario, Canada. My pool builder's plan is to dig, install the metal sides, backfill with concrete, and then leave for the winter (without filling the pool with water). No liner would be inserted until the spring. My question is: is this OK, or would there be a problem with shifting of the structure due to freezing water/ground around the pool, without the weight of the water within the pool to "keep it in place"? This is additionally concerning to me, since they encountered water at about 7 feet of digging. I have no idea, but I thought I should ask another opinion to be safe. Thanks!