Elastic Settlement

[Okiryu]

Hi, when calculating elastic (inmediate) settlements in unsaturated silts due to fill placement, how do you consider "B" and the shape/rigidity factors in the elastic settlement equation? Since the site covers large area, "B" is very large so elastic settlements will be very large as well. I understand that for this type of one-dimensional loading, and in case of saturated fine-grained soils, elastic settlements can be neglected, but this is not my case, where silts are unsaturated. BTW, I do have information for the soil modulus, so does the elastic settlement can be related simply to the strain value from Hooke's law equation?

Thanks for your support.

 

[Ron]

"B" is very large so elastic settlements will be very large as well.

Not so. That depends on the depth of fill and the soil stratification....not only the classification, but the proximity of the stratification to the fill.

Yes..you can compute elastic settlement from the modulus and Poisson's ratio.

 

[Okiryu]

Ron, for unsaturated fine-grained soils (silts), what do you think about calulate settlements based on consolidation theory and assume that the setttlenment will occur fast (based on Bowles, approx. 7 days)?

 

[fattdad]

use Bousinesq or Westergard to determine the change of vertical stress with depth.
make sublayers that convey variation of modulus with depth.
use elastic theory to calculate the compression that will develop in each sublayer owing to its modulus, the sublayer thickness, and the change in stress (this is akin to pl/ae).

f-d

ípapß gordo ainÆt no madre flaca!

 

[Okiryu]

fattdad, using pl/ae, means assume that Hooke's Law can apply (modulus=stress/strain), is this correct? If this is correct, Poisson ratio is not considered in the analysis. Is this because, the compression due to fill can be considered as a one-dimensional loading case?