Compaction Grouting is probably a solution you are looking for. Pin Piles/Micropiles will be probably more expensive as it will require structural slab/grade beams. Compaction Grouting can be done in phases to keep the traffic open.
Liquefaction is a concern and should not be taken lightly. liquefaction concerns can be as deep as 55-60 ft. I suggest stone columns or other ground improvement methods that fit your site constraints. You need to densify the soils so the potential of liquefaction is reduced.
Loike fattdad said, site characterizxation and appropriate ground improvement method will do fine. You can insllaanchors, helical piers, micropiles, Dynamic Deep Compaction, etc. depending on the soils and loads. check out www.haywardbaker.com for different site improvement methods.
There is a geotechnical company www.haywardbaker.com, they are a large design-build contractor. they can do dynamic compcation, helical piers, steel piles, or can provide other economical solution depending on site conditions. I had good luck with them as they do have several techniques.
What if the building settles as RAP was not designed to the right depth or adequate diameter was not constructed. Modulus Test/Plate Load test is meaningless without utilizing basic soil mechanics. I think Engineer of record is liable, even for all design build work...isnt that true?
I agree with you "dglittle" on the soil mix columns, that they need to be constructed as a "cell" element.
I made no commenst about jet groutng, but sure can be used in cells smililar to soil mix columns.
Stone columns shall work with simple area replacement ratio because they are not as stiff...
You can utilize reinforcement effect of stone columns (proven by Finite Element Analysis), you can come up with a area replacement ratio (11-20%) to reduce liquefaction risk. You may also look at soil mix colums in lieu of stone columns. I will suggest you to call Hayward Baker.
You can put a steel rod in the center or do a soil anchor between columns for uplift. Uplift capacity can be provided with any aggregate-pier system. Check out FAQs at the above refernced website.
I just want to re-emphasize that if the design is for liquefaction mitigation, post construction CPTs and/or SPTs between the columns is warranted. Plate load tests does not tell you anything if you are mitigating liquefaction potential.
I recommend post construction CPTs or SPTs as the best ways to check the quality of ground improvement for liquefaction mitigation. If this is for bearing a plate load test with the engineering judgement of the "geotechnical Engineer" (not the design build contractor) should be adequate.
For...
You do not ned to worry abour water table, use some other aggregate pier system like Vibro Piers. It can be installed by dry bottom feed method. Checkout www.vibropiers.com or http://www.haywardbaker.com/services/vibro_piers.htm
family of aggregate piers (geopiers/vibropiers/impact piers/etc...) are tested by plate load tests, normally a 36" plate load test is used. Please note that a 10 ft long pier will show you the same result as 20 ft long pier because the size of plate is too small. Therefore, make sure that...
Stone columns/vibro piers/geopiers/rammed aggregate piers has same stiffness. It is a hole filled up with gravel. A simple check - take a 1 cuft of box, take 3/4 inch rock and denisfy it as much as you can - you will find that you cannot densify it much, therefore these all systems create a...
