Slab on grade with drilled pier system

[EARK]

When drilled piers are required and grade beams with foam underneath, is the slab on grade generally to be designed to span between the grade beams?

 

[la belle vie]

Generally Yes. You need to design the slab to span between the grade beams, and the grade beams to span between the drilled shafts. You can pour the concrete against the soil, but over time the soil will settle relative to the shaft supported grade beams.