Saturation of clay below a water table

[kcall2]

Gents,

A site in an alluvial deposit has a water table ranging in depth from about 18 to 24 ft (based on boring logs). The soil from a depth of 10 to 30 ft is a clay, generally consistent in color (munsell), water content (25 - 35%), dry density (85 - 95 pcf) and fines content (75 - 95%). Below 30 ft is a stiff sandy lean clay. Can a clay below a water table have unsaturated zones, or at least appear unsaturated?

The adjacent property was dewatered to a depth of 40 ft during conctruction of an underground parking lot using dewatering wells. Two years following construction the adjacent site was drilled using a hollow-stem auger boring. Measured depths of ground water table (prior to dewatering and about 3-4 years later) were consistent. However, upon examing samples below the water table they did not appear saturated. Using an assumed specific gravity for each sample the degree of saturation ranged from 90 to 100%. It is odd considering the dewatering contractor on the adjacent site had problems keeping up with the rate of water flowing into the wells, and that it was dewatered to 40 ft.

Thanks for any comments.

 

[ekincia]

hi everyone
I am working on a phd project where we \re using Lambeth group clay (LL 60% PL 26% OMC 19% particle density 2.7)I have collected disturbed samples from site and remolded them into 100mm dia 200mm length mould applying specific compaction effort. I am trying to saturate the sample in triaxial equipment aplaying 50kpa cell and 30 kpa back presure. I have been waiting for few days and there is no hope. Anyone has any saggestions for making saturation process faster.Concern is that during compaction samples from the site chopped into 10 to 15mm small pads and brought to OMC inorder to simulate site condition. I think this is causing some discontinuitys within the sample and not allow full saturation. Any comments, new ideas can help.
Thankyou

 

[fattdad]

increase your back pressure saturation. That's the only way once it's in the triaxial cell. (Note: you have to increase the cell pressure too so you don't impart greater effective stress.)

f-d

¡papá gordo ain’t no madre flaca!

 

[ekincia]

fattdad thankyou for your respond. Can I do anything before putting sample into triaxial cell? or do you know any other methods of saturating sample.

 

[Ron]

ekincia...post your question in a new thread, not tacked onto an older one. This will give everyone an opportunity to see your question without having to wade through a bunch of irrelevant stuff.

You're fortunate that fattdad is a regular in the forum and answered your first question....

 

[fattdad]

(Ron's right, buy the way.)

Is this a compacted sample? If so, you can compact it as wet as possible.

f-d

¡papá gordo ain’t no madre flaca!