slab on grade vs. spread footing

[ohyeh]

To do a site investigation for a slab on grade, do we also investigate to 2 or 3 times width? If not, will the soft zones within 2 to 3 times width will become a concern?

Also, does anybody have experiences on constructing mini-storage facility on 4 to 5 m thick uncompacted fill? If it is doable, what will you recommend?

Thank you!

 

[civilperson]

Remove fill and replace as a controlled structural fill. Soil is cheap and even with forgiving metal buildings the pavement repair costs due to soil failures will be greater than the soil rehab expense.

 

[cyclinggeo]

Another approach may be to use a combination of over-excavation, use of a geotextile (fabric and/or grid), and backfilling with structural fill.

Cheers,

Z

 

[csd72]

Multi level storage racking is very sensitve to floor flatness.

 

[oldestguy]

I asume this is a series of connected garages, right?

If so, I'd try some cheap earth surface applied compaction, such as a fully loaded quad axle dump truck giving at least two tire tracks per each area. Drive in lowest gear at low speed.

Then use a "slab-on-grade" as the foundation, reinforced with something better than roll-out netting. If a structural engineer is involved, tell them to design for any area 3 meters square as having nothing under it.

This is a cheap, reasonably suitable treatment.

Another way, can you dig up enough nearby fill material to "roll" a surcharge over the site? That will give some compaction to the fill. Ideal surcharge height is at least 3 meters.

This also is a cheap procedure, but not as good as the replacement and compaction procedure mentioned above by CivilPerson.

Owners of projects like this should be told what risks are there for different alternative treatments. When given these facts, I have never had one backfire with a complaint or court battle over these cheaper treatments. Matter of fact, I usually am surprised at how well they work.