Outdoor Enclosure bottom?

[Oogway the russian tort]

So, I haven't been able to build a tortoise enclosure in my backyard but NOW I CAN! So i was wondering what you guys use to secure the bottom of your enclosures since Russians are notorious diggers. I've heard people using wire, digging extra 2 feet deeper, and cement. I didn't want to use the wire in fear of it not being secure, and digging to deep isn't a option ,because i might hit a water line. My only option leads to cement so how do you guys lay the cement? Compact it a pour it on or what else. Thanks.

 

[ZEROPILOT]

Back when I made an enclosure like that, i buried some flat cement slabs around the parimeter of the enclosure. Then covered it on soil and mulch.
Later I found that my tortoise....A Redfoot...didn't dig.
Those pads are still buried out there, too.

 

[Blackdog1714]

OLD Predator trick for coops- bury heavy guage wire two feet out from fence like an L and bury. That way if they go to the base of the fence they will never dig or out.