I really think you should get her a playpool (or build her a small box, like a sandbox) and fill it with dirt for her to dig in. It obviously relieves her tension, so I'd give her a place and teach her that it's ok to dig. Really tamp the dirt down hard and don't use sand. And of course in combination with that, any of the above methods to deter her from digging in the spots where you don't want her to.