"The reason [another "slow" explosive called ANFO is] used in mining [versus RDX or HMX] is because it has a slower reaction rate, producing gas and shockwaves that shove rather than shatter." I believe this is corroborated by the Cooper book you suggested earlier.
This is essentially correct, as brisance is shattering power, and it is measured in detonation velocity. However, in concrete, higher velocity explosives don't give as good of breakup. It's weird. Rocks, I'm not for sure about; I do know that even if ANFO is wanted for its slower Vdet
wanted for its price.
The problem with trying to figure out heated gas, etc., is that you are pushing all that air in the building out of the way, and that compresses it. Personally, I think it's a fairly complicated fluid dynamics problem with the gaseous friction of the compressed air on the undisturbed air, etc. Regardless of what the equation is, you'd be much better off starting with something like cuprous acetlyide, where you know that no gasses are produced, so you don't have to worry about that, and then figure out how much air is moved from the explosion. It is a very complicated issue.
Another book to check out is: Numerical Modelling of Explosions or something to that effect. It's on Amazon, too. You need to really be up on your math to understand that, though, as it's mostly calculus. However, it does go into detail on what you're talking about. I read through it, found out it wasn't what I was looking for, and never purchased it. The Cooper book is enough for me. Buy books. Seriously, it's the only way you're going to be satisfied with the answer.