Or HaChaim on Numbers 16:33/אור החיים על במדבר ט״ז:ל״ג

1 וירדו…חיים שאולה, they descended into Sheol while still alive. The earth did not kill them but they remained alive so that the bowels of the earth became their Gehinom. The reason the Torah did not say חיים לשאול, but חיים שאולה is that although generally speaking when a word should have the letter ל at the beginning, the letter ה at the end of that word can substitute for the missing letter ל at the beginning, the Torah does not make such changes arbitrarily, without a reason. In this instance the Torah hinted by means of this construction that after Korach and associates descended they did not die but were given the ability to remain alive. This is what is meant by Sanhedrin 100 that G'd gives the wicked the ability to experience their punishment. If they were to die too soon they would not suffer the pain of G'd's retribution. If the Torah had written לשאול instead of שאולה, the meaning would have been that they died as soon as they arrived in Gehinom.