I read this book in 2016. It starts out with how the author was inspired by hypothetical sciences in the early 80's.
The book is about, the US being afraid that the Russians had set off a nuke.
So a base was sort of sunk into the earth. But here's the thing, they are solid to each other, but like ghost. The are able to occupy the same space as solid matter.
It becomes a yearly thing to try and climb a ladder back to the surface. The main character finally does and he Russians had taken over the United States and he is invisible to the Russians at first.
The cover shows a guy, climbing out of a hole in the ground. In a field of wheat being harvested by a huge red Russian tractor.