undrained youngs modulus of clay

[lvkb]

Can anyone give me a typical value of the undrained young's modulus (Eu) for very soft alluvial clays with an undrained shear strength of about 5kPa?

I'm trying to calculate the immediate settlement of a rock embankment on such a material.

Thanks!

 

[dgillette]

I have to wonder whether you are asking the right question.

If the strength is only 5 kPa ~ 105 psf, it wouldn't take much of a fill on it to cause slope instability, mud waves, intrusion of individual rocks into the clay, etc. Initial settlement is probably governed much more by shear strain than by vertical compression.

If it really was just vertical compression, the initial settlement (before there is any consolidation due to dissipation of pore pressure) would be quite close to zero, since, if the material is saturated clear through, the compressibility is governed by the bulk modulus of water. There would be some consolidation taking place during the course of fill placement, however.

Can't say much more without knowing details.