Deep Soil Mixing?

[tocoadog]

Have a site in NM for a large retail center.

Historical research indicates that the site was once a quarry for concrete and we understand spoils were backfilled uncontrolled with little to no compactive effort.

Preliminary borings encountered about 25 to 33 +/- feet of loose to medium dense (N=> 5 to 15) silty gravel with sand. Wc about 3 to 5% (dry to moist). In-situ dry density on the order of about 100 to 105 pcf.

Currently we are considering piers and acipp for deep foundations, but thought deep soil mixing may be an option. Dynamic compaction is not a viable option due to adjacent structures.

My question is...for recommendations in a report, what details and specifics should we illustrate for deep soil mixing? Or is the deep soil mixing proprietory? I don't think it is, so what is usually placed in a report? Specifications? Depth I would assume?

Anyway, any help would be great. Or questions? Or another angle we haven't thought about.

 

[Zoomzoo]

Don't know much about deep soil mixing - but I do want to comment that the WORST soil conditions I've ever seen were in a backfilled quarry (And, I think my quarry was typical). There is no rhyme or reason to the backfilling process and often trash and other debris is thrown in without a second thought. Nobody watches these quarries, and nobody cares what they throw into them - until of course you decide to build there...

So, even if you get your foundations right, you may still have significant problems with roads, parking strips, utilties, etc., etc., and etc.

Be careful!

Zoom

 

[BigH]

Why not consider dynamic compaction - dropping heavy tampers (3o to 40 tons) some 30 to 40 ft from cranes. If your development is single storey, might be a good way to go. There were some case histories published back in late 70s on using such work in east coast sand deposits.

 

[eric1037]

See my response in thread256-147231.