Does Tolkien have any writings about what happened when the dwarves dug too deep, or is that just a side note mentioned to explain why things are found that way? Gandalf had heard some rumors, but wasn't sure if they were true. That would have been an interesting documentary of first hand "oh shit! RUN!"
The Dwarves tell no tale; but even as mithril was the foundation of their wealth, so also it was their destruction: they delved too greedily and too deep, and disturbed that from which they fled, Durin's Bane.' (Gandalf)
In Dwarf Fortress? Absolutely, if you dig very deep, you can find (spoiler alert) adamantine, but under the adamantine you also find the entrance to the Underworld, which is filled with hordes of demons. I've even had it happen a few times during world generation, when some dwarves dig to the Underworld and thus created a new goblin civilization with a demon as a leader, or something like that.