"According to most survivalist sites, ocean containers can be buried, hidden away under the ground outfitted with electricals, rudementary plumbing, and all the food and water you can store for several months of keeping a low profile. While we at American Steel have seen it done, I'd like to give a word of caution. Cargo containers take on their loads and distribute them at all four corners. That leaves the central portion of a steel container unprotected as to how much of a load you can put on top. When you see all those thousands of cargo containers stacked on top of each other in cargo container ships, they're actually interlocked at the corners, like giant Legos. What must be done should you decide to bury your cargo container, is reinforce the roof to be able to take the pressure of earth. Or...go with a berm.
Berms have been used for centuries. Partially burying something was done since ancient Roman times. A partially buried cargo container would still leave the double-swing doors available for access. If you’re the survivalist looking for a nuclear fall-out shelter, than you would need to bury the cargo container under at least 3 feet of earth. Just make sure that there is support for the roof. And make sure that the shipping container you purchase for this is made of cor-ten steel. This steel is nickle-based and prevents rust from eating through to the interior. It will allow some minor surface rusting, but not more than that. Above all else, do NOT purchase aluminum cargo containers for this use! Aluminum can't take the weight ratios and will crumble."
(Found at Uncertain Times)