[vash]

are the pier/piles configured around the perimeter? concrete ones, and do you know how deep (well doesnt really matter i guess). since it is a framed workshed, couldnt you rent some beams, and jacks and pick it up a tiny bit, actually support it, demo out the floor and any foundation, drill dowels and epoxy them into the existing piles, lay down a mesh, or if you get fancy, a simple rebar grid, maybe a gravel pad prior to rebar, do some forming and pour the new floor and a raise foundation, set the woodshop back down, anchor it, and away you go. i wouldnt mix the concrete. get it delivered and hire a concrete pump company. but i dont know your budget.