Long Term Behaviour of Bangkok Clay

[sango]

Dear all,

I am doing a finte difference numercial analysis on a lateral loaded piles in Bangkok Clay.

I have carried out undrained analysis (short term stability checking?) that allows built up of excess pore water pressure.

I need to study the long term stability, My questions are as follows:

(1) Despite change in possion ratio(0.4-0.5 for undrained case and 0.3-0.35 for drained case), is there any reduction in Young Modulus of the Clay in drained case (long term)or Effective analysis is essential in Clay?

(2) Mohr-Columb was adopted in my model. Is there any typical values of Bangkok Clay in drain case? I think that effective cohesion become zero and effective friction angle is a small value (<25 degree).

(3) Only Vane Shear tests had been carried out. Is there any empircal correlation between soil parameters drained and undrained cases?

Many Thanks.

 

[SmokeyBear]

Hi sango,
(1) Elastic principles tell us that Edrained will be about 0.77 times E undrained. [Eu=1.5 x Ed /(1+v')]. However, this reduction should not have a significant effect on the result.
(2) Typical drained values for Bangkok marine clays about 0-3kPa and 24 to 27 degrees.
(3) Vanes ok for a reasonable estimate of undrained shear strength. Should use Bjerrum's correction factor. I don't know of any relationship between Su and c'.

Hope this helps.