I'm gonna say no. You'd be going up against the compressive resistance of the ground. At depth where the pressure is already high, you won't be able to compre

I'm gonna say no. You'd be going up against the compressive resistance of the ground. At depth where the pressure is already high, you won't be able to compress the ground much further even with the extreme force of a nuke, and most of the compression that you do achieve will just bounce back a moment after. At shallow depths it is possible for matter to be pressed to the side, because in addition to being lower pressure and more compressible, matter can be displaced sidewards and up. I imagine shaping the nuke will make a differently-shaped cavern, but still just a cavern.