What are your references? I really enjoy what you have here. The groundwork and I-beams are nice! The overall color tones give me a sense of gloominess or misery. Don't take that the wrong way though, as that is how I feel that life in that conflict was or would have been. Being able to influence emotion like that is rare and signifies success.
It appears that the bunker was scratch built? Are you done with the brick-work on the bunker? If so I would recommend removing the lifted edges around the scribe lines of your blocks. Shut me down if I'm off base here.