Can sonotubes be left in drilled piers? 1

[Kom3]

Hello all,

I designed a drilled pier that is 5' deep with 6" above ground. Upon doing a structural observation, it is found that the contractor used a sonotube for the full length of the drilled pier (from bottom of embedment to top). It is my view that the sonotube can rot since it is made of cardboard and a half inch perimeter gap can form once it rots. Is leaving the sonotube in the ground an issue? Is there any issues from a constructability point of view if they remove the sonotube before they backfill and compact the surrounding soil?

Regards,

 

[BAretired]

I talked to the contractor. The reason why they used sonotubes in the first place was because the surrounding soil was sandy and had the tendency to fall in without the sonotube (similar scenario to phamENG).

That is likely to be true of the piers not yet poured.

After they poured, they just left it there. I talked to the contractor about my concerns and we have agreed that moving forward, they will remove the sonotube after pour or not use it at all.

Removal after pouring may not be possible; smooth steel casing may be required for that.
Not using forms at all is not an option if sandy soil keeps falling in (as it probably will).

I won't demand that they strip the ones already in place for reason specified above. They have assured me that they do compact the soil around the sonotube.

They may compact the soil near the top, but they can't compact all of the soil around the sonotube without excavating to the bottom of the pier.


BA

 

[BAretired]

In the circumstances, perhaps the best alternative is to continue leaving the sonotube forms in place.

BA