Yeah, the twenty foot wide one is a toughie, you could drill several holes with a masonry bit / hammer drill at the center 10' / 6' each side and inject the hydraulic grout there? That would be a long drill bit. . . Who knows, maybe consult with a house mover?
You may have suffered the settlement of backfill that was not adequately placed and compacted.
One solution would be to enlist a concrete contractor that is skilled in placing hydraulic grout underneath to raise the steps, this may or may not work. . . the grout will flow wherever there is no...