Sunni, let me clue you up:
Our bunker busters are designed to bust the best bunker we know how to build using the very best materials and construction, and no one builds a better bunker than us. The Iranians certainly cannot build better.
The very nature of a bunker is to house a facility which is rooms--- airspace ---below ground. The first one penetrates in 200 feet leaving a 25 foot wide hole which is enough alone to reach most bunkers and explode. Since it is an airspace coverted over by concrete, steel and rock, the explosion blows down. Now the facility has to withstand all the weight of the mountain plus the concussive force. This fractures and weakens the structure.
Followed by another bunker buster in the same location. The Earth is now already loose and spread open, the second penetrates deeper and further fractures and damages the structure. Followed by a third.
At that point, no bunker on this planet survives intact. Even if the facility is not totally destroyed, it is now non-operational, with power, light, water, ingress, etc., all disrupted and much of the facility destroyed, damaged or unsafe and uninhabitable.