We had a problem a few years ago. One was digging under our patio slab to make a den. In reading up and asking the local extension agent, I learned they usually have three or four dens, and spend a night or two at each in rotation. If you destroy a den they'll give it up pretty easily. If you can find the den, it's worth a shot.
On a more immediate tack, get some plastic owls. Owls have no sense of smell, so they are skunk's only real predator. I put a couple out, and have not seen one since. I know they're still around, because I'll occasionally get a whiff, or see some damage in the lawn where they dig for insects, but the problem has been reduced to a minor nuisance. Good luck!