Soil compaction with increasing depth

[huey6367]

I am not an engineer (I'm a geologist) but need some advice/information from professional engineers regarding the compaction of soils with an increase in depth. It would appear to be, that a soil (granular or cohesive) would increase in density with an increase in depth due to the load of the overlying soil even if initially deposited in a less compacted state. This appears clear to me from preloading projects I have been involved with. But I am looking beyond a preloading depth (>20 feet). Is there any research information that shows this to be true or am I incorrect about this.

I deal with sinkholes in Florida so a portion of the sinkhole/karst phenomena is the decline in density at depth.

Thanks in advance

 

[Ron]

Density is not necessarily a function of depth, particularly depending on the soil classification. For fine grained soils (clays and silts), there is a tendency for overburden to have a greater affect on the soil density. This is related to the change in void ratio from consolidation of the soil. Soil chemistry can also have an effect, particularly in the karst formations you deal with in Florida. Groundwater solutioning can easily reduce the density of the soil structure, without regard to the depth of that formation.

Essentially any of the classic soils mechanics/geotechnical texts will give you a good treatment of this subject. Here are a few suggestions:

1. Terzaghi and Peck
2. Sowers
3. Bowles
4. Das

Each has multiple texts on the subject, so do an Amazon search and you'll find numerous examples.

 

[fattdad]

Where water tables fluctuate and limestone is turning to muck, developing caves and caving into such voids, the assumption of increasing density with depth seems moot.

Ron provides a general overview and good directions for further information. That said, in the world of geology, we should be prepared for Mother Nature and her inconsistencies!

f-d, p.g., p.e.

ípapß gordo ainÆt no madre flaca!