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.

 

[CarlB]

You can get some general information from ETL 1110-1-185,
"GUIDELINES ON GROUND IMPROVEMENTFOR STRUCTURES AND FACILITIES", which compares and discusses many types of ground improvement. You should be a be to web search a free download.

 

[cvg]

http://www.usace.army.mil/inet/usace-docs/eng-tech-ltrs/

try this for USACE technical letters

 

[VAD]

For the consideration of deep soil mixing you should be talking to a speciality contractor to get some information about the process.

What is the stratigraphy to the backfilled quarry bottom. Is the 25 to 33 ft the fill and below is dense or hard material.

Have you examined the feasibility of precast prestressed concrete piles or open toe pipe piles.

Your cipp piles may be the best option.

 

[eric1037]

Check out Hayward Baker's website for info regarding soil mixing.

http://www.haywardbaker.com

I always thought deep soil mixing was mostly used for soft, cohesive soils.

Have you considered vibrocompaction? You mention that there are nearby structures. How far away are they?

Hayward Baker has test results in sand that indicate peak particle velocities of 0.2 in/sec at 7 feet away from the vibroflot.

We recently did some vibrations monitoring for a site where we had relatively old buildings within about 100 feet of the vibrocompaction location. We monitored vibrations and had peak particle velocities of about 0.08 in/sec at 60 feet from the vibroflot.

 

[Rjakiel]

sounds like your project would be suitable for soil mixing. we would be happy to help in your evaluation of the site. our company specializes in shallow and deep soil mixing. you can visit our website at

http://www.raitoinc.com

 

[cmorgh]

Hi,
Generally you can apply DSM in such a texture. I have been engaged with fairly similar project though that was mostly the protection for a deep excavation in an area having silty sand (saturated) texture. Steel H piles were also inserted into the DSM columns with waling and anchorages. DSM columns had the role of decreasing hydraulic gradient and also somemeans for anchorage system. However, generally it is feasible.
You have to consider vibro compaction method as well. Which of the methods are better? many factors contribute as well as the value engineering.
Regards

 

[Geocontractor]

I believe that Hayward Baker is working on a project right now in New Mexico doing seep soil mixing. I would contact their Texas office and ask for information.

 

[tocoadog]

Thanks for all the responses.

And any sort of dynamic compacton is not feasible on this site. Short story: The owner of the property, a concrete manufacturer, decided against a reputable geotech company in the past. So, structures to the north and east of this particular site, structures that are also located in the quarry, have experienced upwards of 4 to 6 inches of distress. And one of the structures is a condominium complex. Safe to say he is considering different options now...and safe to say anything dynamic is toooo risky.

Again, thanks for everyones response.