socketed drilled shaft permanent casing

[m.scofield]

IBC 1810.3.9.6 indicates: "Socketed drilled shafts shall have a permanent pipe or tube casing that extends down to bedrock and an uncased socket drilled into bedrock, both filled with concrete." Any ideas why IBC requires permanent casing vs. temporary casing?

 

[dhengr]

M.scofield:
They don’t want mud and crud falling into the socket.

 

[WARose]

Socketed into bedrock, you've got your form.....as to why it would be permanent in the soil.....you'd probably do some sort of damage to the pile (or break the rock socket bond) trying to withdraw it.

 

[m.scofield]

I would expect a temporary casing may be required because of the transition from earth to rock. But I visited a number of drilling and DOT web sites and none of them indicate that permanent is necessary or required.

 

[WARose]

But I visited a number of drilling and DOT web sites and none of them indicate that permanent is necessary or required.

And how was that conclusion arrived at? (And by whom?)

 

[m.scofield]

ACI 336.3R-93 3.6 also describes Piers socketed in rock as "...The drilled pier consists of a heavy wall permanent casing fitted with a cutting shoe and seated into the top of rock." I believe there is an ACI 336.3R-14 out but I don't have a copy to see if they've changed this description.

 

[BUGGAR]

The ones I am experienced with (North River Sewage treatment plant built out over the Hudson River on something like 2400 cased and socketed piers) had no concrete reinforcing below the top cage. I think these where designed for axial load only. There were no interior shear ties on the casing.

 

[WARose]

Usually the codes (like 336) recommend some type of liner that will allow withdraw (if desired). Usually it’s some type of corrugated pipe (as the liner).

But for rock socketing.....I'm not sure if I've ever used anything but permanent casing.