Shanshep method

[ypyenpham]

Hi, everyone

I'm working a project. They request to carry out CIUC test (incremental stage). They perform the Shansep method analysis. I don't understand the Shansep method. Everyone can direct and explain that method for me.

Thanks!
yp

 

[dgillette]

Start by studying CC Ladd's Terzaghi lecture:

Ladd, C.C. (1991). "Stability evaluation during staged
construction (22nd Terzaghi Lecture)." J. of
Geotech. Eng., 117(4), 540-615.

It will take a bit more than CIUC tests to do a proper SHANSEP analysis.

 

[fattdad]

If I remember. . . .

the undrained shear strength of a fine-grained soil layer is dependent on confining stress. For normally-consolidated soils, this relationship is typically 0.2. It can vary from this value and it can also be affected by OCR. I'd consider this a request to assess the Su/P ratio and to what extent the soil is overconsolidated. Using these relationships, you can then better model the strength in the area under stress.

Then again. . .

f-d

¡papá gordo ain’t no madre flaca!

 

[dgillette]

The strength ratio is actually very sensitive to stress path and consolidation conditions. A CIUC test like the OP has can indicate shear strength nearly double what you get from CKoUE, for example. Chuck Ladd explains it all in detail in the paper.

 

[paganel]

The principal is that the shear strength determined by the consolidation state.
I think the aim you want to carry out SHANSEP analysis is that want to get preoconsolidation stress from this concept. Or maybe you have already make a lot of CPTU test,and want to get some correlation with the interpreted Su and preconsolidation stress.

I agree with dgillette that you need more info to carry such analysis.
1\Determine the preconsolidation stress with oedometer test carried out on samples with higher quality.
2\Get the strength ratio. Su\p' from maybe VST.As mentioned this value commonly range from 0.2-0.3,and could vary with different stress path.

Only after that, you can start the work and try to get some reasonable results.

One reference from T. H. Seah and K. C. Lai,Strength and Deformation Behavior of Soft Bangkok Clay is attached, hope can give you some guidence.

 

[ypyenpham]

Thank paganel!

But I don't know what purpose of this Shapsep method. My specialist is laboratory testing and I don't understand the foundation or improvement soft clays. This me

 

[gongxu1492]

recommend a paper by Ladd and Foott (1974).