I think I might just fav this and use it to test my bombs... Alongside my own bunker, and the more famous "Nuclear Bunker" I usually do when there is a bunker built with ligit materials that my bombs have a hard time getting through. (I use the bunkers to better my bomb strenghts)
Bomb just tore right through; Altough, putting it underground is smart as you have all that sand, which has a relatively high melting point, as your first defence. Good bunker +1