Tony Hwang wrote:

Alan Smithee wrote:

Hi,
Mud jacking?
Tony



That's what I was thinking. But I've never seen it done to a basement
floor.


Hi,
Basement floor is sort of floating concrete pad. They are not attached
to the walls. It can rise and sink. Maybe it was sinking unevenly?
Mud jacking will raise it up or prevent further sinking. I had it done
once on my back yard patio pad. Just a guess though.
Tony

If they are poured correctly, the concrete is poured so that at least
part of it lies over the footings, therefore it may rise, but it will
not sink unless it takes the footings with it, or it cracks and sinks
inside of the footings.