[Fuzz]

Originally Posted by TherapyforGlencross

It’s not exactly surprising the bunkers weren’t destroyed.

The bomb weighs 14,000kg and is dropped from 12,000 meters, and let us assume that it may not reach terminal velocity and was not propelled it will smash into the ground with 1.65 billion Joules of energy.

Now, one blow from a SPT hammer is ~ 500 Joules. In engineering/geology refusal is 50 N counts (blows), which usually equates to 0.45 meters. Thus, 25,000 Joules of energy. The bomb would penetrate 28 meters into material that meets the SPT refusal requirements which would be considered hard clay.

The fordow complex is overlain by mountains, so let’s assume a dolostone/limestone mix. Using Young Equation (moreso a model), and you’re looking at approximately 6m penetration. Assuming that the limestone is deformed, you could potentially see a 100% increase, perhaps more, so about 10-15 meters of penetration.

Not exactly surprising to see the US admit that they didn’t collapse the entire structure.

The MOP is reportedly able to penetrate through about 18 m of reinforced concrete with a compressive strength of 5,000 psi.[32][33] Iranian domestic research has produced concrete exceeding 30,000 psi, a level that could sharply reduce the bomb’s effective penetration depth.[34] Complicating matters further is the possibility of deflection or yaw caused by advanced bunker-shell construction techniques.

https://en.wikipedia.org/wiki/GBU-57A/B_MOP

Apparently the rock above the concrete there is also really really hard, so it was never a guarantee of success on this one. I think it was more wishful thinking and "what have we got to lose?" (that's rhetorical for us, not for their brains).