Continuous Footing Under Pile-Supported Wall?

[mrengineer]

This is a survey: Do you show a continuous footing or mud slab or nothing below c.i.p. basement walls that span between deep foundations? Do you put a note on the drawings that slab-on-grade adjacent to bottom of wall must be in place prior to back-filling behind the wall?

 

[structuralaggie]

If the wall is designed to span between piles, similar to a tilt wall, there is no reason you have to have a footing. Just make sure the bottom of the wall is deep enough below fin. grade.

If the stability of the wall is dependant on the slab, then it must be installed before backfilling. If support at the top of the wall is requried, then the floor has to be installed also before backfilling.

In this situation, I prefer to pour the piles, then a grade beam (which is designed to span the piles) monolithically with the slab, then the wall. So this way the wall doesn't have to span the piles.

 

[dik]

Sometimes use a void form between piles. When the contractor forms the wall, the forms just go to grade, supported by stakes and gravel bedding and the gravel extends to the face of the form to keep the concrete from leaking out. I've never seen a mud slab or footing used... only time footings are in place is an existing condition and the wall is underpinned using piles

I use a note that the contractor is to provide for lateral support at the top and bot of the wall prior to backfilling against the wall.

Dik

 

[UcfSE]

I would have a grade beam across the top of the piles. It may be cast integrally with the wall.