[cypher]

I don't think a 40 gallon tank is that small (if I remember the dimensions right!) burrowing is just natural behaviour so maybe you could try burying some cardboard tubes or boxes under the substrate for her to do what she likes with, it might distract her from chewing or trying to chew the tank & encourage natural behaviour.
Add as much enrichment above the substrate as you can too, if you're unsure what she might like have a look through this thread for some ideas.
Let's See Your Cages (May 2016)