"Grounded" is used in the sense of founded, based, fixed in (
Isa 30:32), "and in every place where the grounded staff shall pass, which the Lord shall lay upon him," the King James Version margin "Hebrew every passing of the rod founded," the Revised Version (British and American) "and every stroke (margin "Hebrew passing") of the appointed staff (margin "Or staff of doom (Hebrew foundation)"), which Yahweh shall lay upon him"; following,
Isa 30:31, "with his rod will he (Yahweh) smite him"; Delitzsch, "every stroke of the rod of destiny which Yahweh causes to fall upon Asshur"; the word is mucadhah, from yacadh, "to place," "to found," "to appoint," "to ordain," hence, "appointed rod (of punishment)," seems the simplest rendering.