Wow, maybe I'm just nuts but I just don't see this lifting occurrence as a threat for your project. We have 2 piers (one of them pretty large with covered pavillion) on a pond that freezes. The water level always rises during the winter freeze. That is when we get our topping from the lows of summer/autumn to bring it up to full pool. We are on 6 x 6 treated timbers. I have noted no appreciable elevation change.
I understand the simple physics in play here, but wonder how much they would really affect a 4 x 6 timber. Of course, I doubt that I have seen 8" of ice encapsulate our verts, either. My only concern has been the more likely event of shifting and wind-blown ice floes.
Interesting concern. I would like to hear more evidence of the threat on your project.
