Sounds like she's looking for a place to lay eggs. They can lay egs without a male and they will be infertile. It might be a good idea to put a nice deep (12 inches of substrate) laying bin in the cage. Make sure the tub you use is big enough for her plus a few inches on all sides including above her. Try to use an opaque tub and fill it with organic fertilizer free soil or clean play sand or a mix of both. Make it moist enough to hold a tunnel but not muddy. Make sure not to watch her dig or she may abandon the hole. If she doesn't find a place to lay her eggs she may become egg bound and can die if she does. Give her lots of water and food afterwards. After a few weeks cut back on food so she doesn't make a huge clutch next time.