After a bad water infiltration issue, I started investigating around the main problem area in our machine room. There was what appeared to be a long surface crack which ended up being a diagonal crack right through the 6" slab. It extends under a wall on top of which (I believe) rests our staircase.

My idea was to temporarily cut the bottom plate so I could open the crack (concrete saw and/or jackhammer) and pour new concrete, but there’s a stud right on top of the crack. Any ideas how to best approach this?