I don't see why not. As long as it has walls he can't climb, and he can't dig out, it should contain him. Are you talking about the framework for an above the ground swimming pool?
Just make sure he can't dig out. You can place some bricks or rocks along the inside edge to deter digging. Something like that would make a nice, big enclosure, but would be a bit hard for you to get in there and feed, water and care for the tortoise.