What does teh stress path tell you about the history of a soil.

[deks123]

Hi,

I was wondering if someone could tell me what the stress path of a clay would tell you about its geological history? Also any examples of certain features of the stress path that show specfic history would be much appreciated

Thank You

 

[BigH]

Take a line 1H:3V from the starting point goint up to the right (this is the "drained" path. if the stress path is on the right side of the line, it is overconsolidated, if it is to the left of the line it is normally to lightly overconsolidated.

 

[dgillette]

A note of caution:

Depending upon where you live and where you were educated, p' (horiz. axis for the stress path) may be defined differently.

As I was educated, and apparently Big H was also, p' is (sigma'1 + sigma'2 + sigma'3)/3. In a triaxial test, sigma'2=sigma'3, so this is usually seen as (sigma'1 + 2*sigma'3)/3.

At least in the US, p' is often? usually? defined as (sigma'1 + sigma'2)/2. If that's what you are dealing with, Big H's 1H:3V line would be 1H:1V.

DRG

 

[BigH]

thanks Dave - It was from memory! . . . and it was octahedral stresses . . .

 

[amraam35]

In a laymens term summary, a stress path will tell you if the soil is over under consolidated (uncommon, unloading stress condition), normally consolidated (never been consolidated more then that), or over consolidated (was once more heavily loaded, was compressed more then it is now and has since "unconsolidated").

In terms of geological history, an normally consolidated soil would be once that has not been stressed more then it has been now. A residual soil, formed from bedrock weathering, a soil placed from water deposits, etc, could be normally consolidated. An over consolidated soil could be a soil that was placed and then had the overlying soils eroded away, or could have been under a glacier and the glacier traveled over it and melted away, for two examples.