In order to accomplish the door, as Peaca&Love said you can't tie two entities to one object, so you'll have to make Two exact doors one func_breakable and two func_door, then set them up to be triggered by an env_render
Like this...
If your going into the tunnel have the door open (this doors name is door1- Its a func_door or doorrotating) then you enter the tunnel and the door closes.
Now where the door closes is the exact point where the func_breakable door is located only that its invisible because you set the env_render to make it so. Now set up a multi-manager to trigger the first env_render to make the func_breakable appear, and then one second later trigger another two make the func_door dissapear, so now instead of having a func_door that closed you in its replaced by a func_breakable door, now have the door to explode(when triggered) and have to grunts repel down(I did this with a map once it was cool, But my tunnel was going up with a ladder, when I reached the bottem it happened) so there you have it, enjoy.