... caught up in cold War fever of technology, the use of Atomic Explosives was proposed for many civil engineering projects. Including this 1946 article from 'Popular Mechanix". Why use plain old TNT to build a canal, or level a mountain top, when you can do it cheaper and much faster with an atomic bomb! It sort of made sense. Nuclear explosives were millions of times more powerful than old-fashioned chemical explosives.
'Operation Plowshare' was the Atomic Energy Commissions attempt to find 'peaceful' uses for nuclear weapons technology. Between 1961 and 1973, twenty-seven nuclear detonations were conducted to test the feasibility of everything from creating harbors to extracting natural gas from rock. Some ideas seemed to work, others didn't. One problem persisted. Everything was wildly radioactive. There were dim promises of special designs for extremely 'clean' atomic explosives whose residual radioactivity would have been lessened. These 'kinder-gentler' bombs never came to be and the project fizzled out under the weight of it's own absurdity.
Here is Edward Teller, one of the most notorious 'Strangelovian' characters, explaining it all to us in a recently de-classified film.