How to auger a 18" hole through sand that's collapsing

[jaotguy]

bentonite = clumping kitty litter

 

[Ken45101]

Some years ago, I saw them doing the piers to support an interstate ramp in Cincinnati. They had to drill 100' deep through sand to reach bedrock. They used an 8' auger with a steel casing around it. I believe the casing sunk as they drilled. When they reached bedrock, they filled the casing with rebar and concrete. It was quite a project.

 

[Midniteoyl]

If you do use a sonotube, why remove it?

 

[orezok]

If you do use a sonotube, why remove it?

For the sonotube to drop down into the hole, the hole has to be bigger than the sonotube. This would leave a gap around the footing.

 

[Gary Fowler]

Wetting the sand would help, but a faster option might be to just dig the hole out with a large bucket on a backhoe, set your do-nut and column and backfill with wet sand. Dismiss the drill truck after getting the holes completed in the clay. The drill truck is costing a bunch of money.

The one time we had to put casing in loose sand, we used the drill truck (very large truck) to drill in a casing first. The drill truck had a cross bar that fit into a 30" piece of schedule 80 pipe that had loops cut in the top so the bar would set in and lock in place. The bottom of the casing had slotted teeth to cut into the soil. They drilled in the casing, then put on the drill and took out the loose material, set the rebar, pumped in concrete and withdrew the casing slowly as the concrete filled the hole. The casing was only about 12 feet long which was all we needed to get to the bottom of the loose material but I assume it could have been made longer if needed to go deeper.

Other times we used bentonite slurry to fill the hole as it was being drilled, rebar cage was then pushed in thru the slurry and concrete pumped in displacing the slurry. It took a lot of slurry as the last 10 feet of the hole had a lot of mud and other material that could not be reclaimed. It sure made a heck of a slimy mess also.

 

[Midniteoyl]

For the sonotube to drop down into the hole, the hole has to be bigger than the sonotube. This would leave a gap around the footing.

Gotcha.. too early in the morning

Though, i was thinking that if you used an 8" tube with an 8" auger and the sand collapsed around the tube anyways.... ?

 

[Dr Dave]

We have to auger through 5' of compacted sand and into the virgin clay for the columns on a Pole Barn. Problem is the sand just keeps collapsing. Cleary Buildings is doing this.

Now trying to figure out how to do this. Someone from Cleary mentioned using a 20" sonotube around the auger, but they said it won't work. They said you can't push the tube down with the auger.

I think it would be worth giving it a try, but they don't want to. You guys got any ideas or and experience with using the tube around the auger?

Out of 35 columns, 11 are in deeper sand.

Thanks for any help you can give me.

Ed

I would go get a tube and try it. As the sand falls in the hole the tube should slide down. If this doesn't work try a 20in.x5ft. Peice of pipe. Torch 2 holes hear top 180 deg, across from each other so you can pull it out and reuse on the next hole.

I saw a tv program were they were building a home on the beach, they used a tube about 10 ft. long. After the hole was dug, they pumped in concrete and pushed the water out the top of the tube. They then pulled the tube and went to the next hole.

Dave

 

[masscity]

Just talked to Cleary and they're looking into sonotubes or drums. I also tried to talk them into getting steel tracks for their wheeled skidsteers.

The wheeled skidsteers spin to easy and they bottom out on the sand. They use an auger and a boom on a skidsteer to build the pole barns.

They postponed me for two weeks while they do another pole barn 60 miles southwest of me and work on the tubes, drums and tracks.

Thanks again.

Ed

 

[RxRatedZ71]

Just get your shop vac out and suck on the sand while pressing down on the sonotube. Sorry, just thinking out loud.

Sent from my Motorola Moto X using TractorByNet

 

[orezok]

One of the things I would be concerned with is if the sand is that loose, what level of uplift degradation or lateral movement support will be achieved? I believe that you will have to deepen the footings into the harder material to achieve the engineering requirements.

One of the major calculations for buildings is the uplift. You might find out that in a significant wind that the footings will pull right out of the loose sand.