The more I think about it (see Discussion), the more convinced I am it has to be local thickening of the floor slab where it sits on the piles, to better resist the concentrated forces there. You might also say "thickened slab at/above piles", etc.

A THICKENED SLAB is a portion of a slab that is deeper than the rest of the slab. This is usually done TO INCREASE CAPACITY IN A SPECFIC AREA. In a warehouse for example, a slab is usually thickened at the truck bay door because this area sees more activity than the rest of the floor. If not for the thickened section, would be more likely to crack. Floor are also thickned to accommodate machine loads and vibrations, then reduced between the machines. Simarly suspended slabs may be thickened if the spacing between supporting joists must be increased in a particular area.
http://www.eng-tips.com/viewthread.cfm?qid=2363&page=75

CLL has developed a proprietary foundation slab design known as the "Pile Pad" foundation system, involving a THICKENED SLAB PERIMETER supported by driven timber piles
http://www.contractlandscapes.co.nz/wa8ab4.html

Click here for info on Timber Pile Design and Installation ... Probe entire slab area including any load point piers or THICKENED SLAB AREAS ...
www.hoidaseng.com/services.html