10ft square x 40 deep shaft - how to construct 1

[danvines]

We are starting design on what is mostly a fairly straightforward light industrial building - steel frame, metal panel skin, etc.

One of the pieces of equipment that will go into this building requires a 10' square x 40' deep shaft. This is outside the range of anything we've previously done. We've been brainstorming ideas, but constructability seems to always come up short.

Any ideas or directions as to where to start would be appreciated.

Thanks
Dan

 

[ishvaaag]

You can do in whatever the ways used to do such holes, ranging from manual to sinking a prefab concrete box, or a number of sections one upon other like that. First of all, you need geotech info, sinking unto rock won't be feasible, for example (you could micropile the perimeter and use square frames to keep the micropiles in place whilst further excavating from some level, etc. If muddy liquefiable and so on you may need to use sheet pile etc. Different problems will cause to use different solutions.

 

[JedClampett]

If it doesn't have to be square, you can use a caisson type construction. Sit a precast section on the ground. Excavate inside of it. As it sinks into the ground, add another section on top of it. Forty feet is not all that deep.
Actually, I'm not even sure that couldn't be done with a square section.

 

[ToadJones]

Not sure of the exact dimensions but I have seen sheet piles driven for press foundations then the inside was excavated. 10'x10' is pretty small though.

 

[dcarr82775]

If it doesn't have to be square you could drill a large diameter shaft, install a corrugated steel pipe as a form and cast a concrete ring outside of it. We have done this for some mine access shafts to get to bedrock.

 

[JLNJ]

For sewer interceptor access I have seen where they install the heavy gauge corrugated caisson (in several pieces) around the circumference, undermine, install the next section, repeat.

 

[dicksewerrat]

Look at what actual dimensions you need and then compare to 10 x 10 box culverts and 12 x 12 boxes. The boxes have a 45 degree section in each corner. Do as Jed said, set one in shallow hole. Then set another and excavate in side and let them sink. Seal all joints with grout. But first get your boring logs at the location of the shaft.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[ztengguy]

maybe something like this

http://www.conteches.com/Products/Applications/Wind-Turbine-Foundation-and-Vertical-Shafts.aspx

 

[charliealphabravo]

do you know anything about the soils yet?

 

[PilebuckEngineer]

I am a contractor and I would suggest you just design the area as a precast box or cast in place. Leave the shoring to the contractor. There are plenty of options from sheet pile, soldier pile, secant pile, slide rail, ground freezing, etc. Most contractor have a setup that they use often, but not all have the same thing. We are currently installing some wet wells for a pump station that are 12' did. and 30' deep. We are using slide rail to shore a 20' x 20' x 30' deep excavation.

 

[Teguci]

I think PilebuckEngineer has both confirmed that your project is feasible and has given you the best advice regarding means and methods. I would limit further investigation to a geotechnical report that can be made available to all bidders.

 

[danvines]

Thanks everyone for their replies. After a conversation with the architect this morning, it is entirely likely that a real geotechnical report won't be available until after our bid documents are due. Fun, right?

That said, it looks like we are going to do just as PileBuckEngineer and Teguci suggest and concentrate only on the end result. Having to change our design later on due to unknown soil conditions will be relegated to additional services.

Thanks again.