Having been the principal engineer in charge of a hydroelectric dam and having had to be part of a number of FERC safety inspections, I can say, the use of explosive on top of or near a dam, compromises the integrity of the reservoir until proven otherwise in my mind.
To use your example; popping a pimple on the scalp with a hammer may or may not crack the skull.
Yes, this may have been a military strategic move to prevent Ukrainian troops from crossing the river, especially rail lines, it creates a whole set of problems for the defense of Crimea.
“… Having been the principal engineer in charge of a hydroelectric dam and having had to be part of a number of FERC safety inspections, I can say, the use of explosive on top of or near a dam, compromises the integrity of the reservoir until proven otherwise in my mind.…”
***********************************************************
“Until proven otherwise” would certainly be the appropriate precaution to take. As an engineer (and likely a very good one if you were the principal engineer in charge at a hydroelectric dam) you’ll understand that the Russian engineers (or ‘sappers’ in my possibly out-of-date military parlance) would have used carefully calculated shape charges of appropriate sizes, placed at specific critical spots in the bridges structure to cut or pulverize/weaken the structures to destroy the targeted spans. And those spans would have been dropped in such a way that reconstruction would be difficult and possibly impossible while under Russian fire control.
They also would have tried to do it so as to minimize the possibility of damage to the dam itself. BUT… you never know. 🙀🙀🙀