Dog wont stop tearing up floor?

My roomate and I have an English Mastiff puppy (about 8+ mths). Every night before bed when let both dogs out and lock the Mastiff in the kitchen after going outside, where there's linolium flooring. 2-3 times a week she's ripping it up. WHAT DO WE DO? We're trying to avoid kennels due to lack of space. Anyone have any other ideas on how to make her stop? The pieces she's ripping up are getting larger and larger each time! Please help!? thank you!