Estimating Soil Excavation Quantities in caissons? 1

[MitchMolly]

I need to estimate soil excavation quantities from caissons drilled through fill, marine clay, and glacial till to depths of approx 150 feet. How would the hole be drilled? Do I assume a straight shaft or should I consider telescoped casing, and if so, what is the change in hole diameter with length? Thanks!

 

[PEinc]

It seems that you know little about caissons. Why don't you call a local caisson contractor to discuss the project? You might even learn something about caissons.

 

[BigH]

See Teng's book on foundations - if I remember right, he has volumes/dia already listed. I think PEinc hit it on the head - why not pick up a copy of Bowles - or better Tomlinson and read up on the subject first? I gave a presentation to the Calcutta Geo Group a few years ago on the subject - there is a lot of information out there - file to big to send.

 

[Panars]

Drilled shafts are used quite a bit in transportation projects. You can download the FHWA manual on drilled shafts from this website:

http://www.fhwa.dot.gov/bridge/geopub.htm

This manual includes construction procedures and design methods.

I would guess that a contractor would try to use temporary casing through the fill and then use a slurry method through the clay. The glacial till would probably stay open without slurry, but the marine clay above it would usually require some support. If this procedure was used, then the hole would be a constant diameter for its full depth.

Telescoping casing is usually done in 6-inch increments in the USA.